From: Pratik Patel <prat...@codeaurora.org>

This driver adds support for the STM CoreSight IP block,
allowing any system compoment (HW or SW) to log and
aggregate messages via a single entity.

The STM exposes an application defined number of channels
called stimulus port.  Configuration is done using entries
in sysfs and channels made available to userspace via devfs.

Signed-off-by: Pratik Patel <prat...@codeaurora.org>
Signed-off-by: Mathieu Poirier <mathieu.poir...@linaro.org>
---
Changes for v2:
 - Fixed typo in struct stm_node documentation
 - Added CPU_32v3 to list of architecture STM can't work with
 - Removed unused code (readq_relaxed())
 - Reserved first 16 channels for kernel usage
---
 .../ABI/testing/sysfs-bus-coresight-devices-stm    |   62 ++
 Documentation/trace/coresight.txt                  |   88 +-
 drivers/coresight/Kconfig                          |   10 +
 drivers/coresight/Makefile                         |    1 +
 drivers/coresight/coresight-stm.c                  | 1070 ++++++++++++++++++++
 include/linux/coresight-stm.h                      |   40 +
 include/uapi/linux/coresight-stm.h                 |   23 +
 7 files changed, 1292 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-coresight-devices-stm
 create mode 100644 drivers/coresight/coresight-stm.c
 create mode 100644 include/linux/coresight-stm.h
 create mode 100644 include/uapi/linux/coresight-stm.h

diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-stm 
b/Documentation/ABI/testing/sysfs-bus-coresight-devices-stm
new file mode 100644
index 000000000000..3ddb676831ab
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-stm
@@ -0,0 +1,62 @@
+What:          /sys/bus/coresight/devices/<memory_map>.stm/enable_source
+Date:          February 2015
+KernelVersion: 3.20
+Contact:       Mathieu Poirier <mathieu.poir...@linaro.org>
+Description:   (RW) Enable/disable tracing on this specific trace macrocell.
+               Enabling the trace macrocell implies it has been configured
+               properly and a sink has been identidifed for it.  The path
+               of coresight components linking the source to the sink is
+               configured and managed automatically by the coresight framework.
+
+What:          /sys/bus/coresight/devices/<memory_map>.stm/entities
+Date:          February 2015
+KernelVersion: 3.20
+Contact:       Mathieu Poirier <mathieu.poir...@linaro.org>
+Description:   (RW) Controls which entities have been allowed to use the
+               stimulus ports, regarless of the channel they were assigned.
+               Entity definition can be found in
+               include/uapi/linux/coresight-stm32.h
+
+What:          /sys/bus/coresight/devices/<memory_map>.stm/hwevent_enable
+Date:          February 2015
+KernelVersion: 3.20
+Contact:       Mathieu Poirier <mathieu.poir...@linaro.org>
+Description:   (RW) Provides access to the HW event enable register, used in
+               conjunction with HW event bank select register.
+
+What:          /sys/bus/coresight/devices/<memory_map>.stm/hwevent_select
+Date:          February 2015
+KernelVersion: 3.20
+Contact:       Mathieu Poirier <mathieu.poir...@linaro.org>
+Description:   (RW) Gives access to the HW event block select register
+               (STMHEBSR) in order to configure up to 256 channels.  Used in
+               conjunction with "hwevent_enable" register as described above.
+
+What:          /sys/bus/coresight/devices/<memory_map>.stm/port_enable
+Date:          February 2015
+KernelVersion: 3.20
+Contact:       Mathieu Poirier <mathieu.poir...@linaro.org>
+Description:   (RW) Provides access to the stimlus port enable register
+               (STMSPER).  Used in conjunction with "port_select" described
+               below.
+
+What:          /sys/bus/coresight/devices/<memory_map>.stm/port_select
+Date:          February 2015
+KernelVersion: 3.20
+Contact:       Mathieu Poirier <mathieu.poir...@linaro.org>
+Description:   (RW) Used to determine which bank of stimulus port bit in
+               register STMSPER (see above) apply to.
+
+What:          /sys/bus/coresight/devices/<memory_map>.stm/status
+Date:          February 2015
+KernelVersion: 3.20
+Contact:       Mathieu Poirier <mathieu.poir...@linaro.org>
+Description:   (R) List various control and status registers.  The specific
+               layout and content is driver specific.
+
+What:          /sys/bus/coresight/devices/<memory_map>.stm/traceid
+Date:          February 2015
+KernelVersion: 3.20
+Contact:       Mathieu Poirier <mathieu.poir...@linaro.org>
+Description:   (RW) Holds the trace ID that will appear in the trace stream
+               coming from this trace entity.
diff --git a/Documentation/trace/coresight.txt 
b/Documentation/trace/coresight.txt
index 02361552a3ea..a041477698d9 100644
--- a/Documentation/trace/coresight.txt
+++ b/Documentation/trace/coresight.txt
@@ -190,8 +190,8 @@ expected to be accessed and controlled using those entries.
 Last but not least, "struct module *owner" is expected to be set to reflect
 the information carried in "THIS_MODULE".
 
-How to use
-----------
+How to use the tracer modules
+-----------------------------
 
 Before trace collection can start, a coresight sink needs to be identify.
 There is no limit on the amount of sinks (nor sources) that can be enabled at
@@ -297,3 +297,87 @@ Info                                    Tracing enabled
 Instruction     13570831        0x8026B584      E28DD00C        false   ADD    
  sp,sp,#0xc
 Instruction     0       0x8026B588      E8BD8000        true    LDM      
sp!,{pc}
 Timestamp                                       Timestamp: 17107041535
+
+How to use the STM module
+-------------------------
+
+Using the System Trace Macrocell module is the same as the tracers - the only
+difference is that components (entities) are driving the trace capture rather
+than the program flow through the code.
+
+As with any other CoreSight component specifics about the STM tracer can be
+found in sysfs, with more information on each entry being found in [1]:
+
+root@genericarmv8:~# ls /sys/bus/coresight/devices/20100000.stm
+enable_source   hwevent_select  power           traceid
+entities        port_enable     status          uevent
+hwevent_enable  port_select     subsystem
+root@genericarmv8:~#
+
+Like any other source a sink needs to be identified and the STM enabled before
+being used:
+
+root@genericarmv8:~# echo 1 > 
/sys/bus/coresight/devices/20010000.etf/enable_sink
+root@genericarmv8:~# echo 1 > 
/sys/bus/coresight/devices/20100000.stm/enable_source
+
+From there user space applications can request and use channels using the devfs
+interface provided for that purpose:
+
+root@genericarmv8:~# ls -l /dev/20100000.stm
+crw-------    1 root     root       10,  61 Jan  3 18:11 /dev/20100000.stm
+root@genericarmv8:~#
+
+The following sample program provides an example of the supported operations:
+
+#include <stdio.h>
+#include <fcntl.h>
+#include <string.h>
+#include <linux/coresight-stm.h>
+
+#define BUFSIZE        20
+
+int main(int argc, char *argv[])
+{
+       int fd, n;
+       unsigned long options;
+       char buf[BUFSIZE];
+       char data[BUFSIZE] = "this is a test";
+
+       fd = open (argv[1], O_RDWR, 0);
+
+       if (n == -1) {
+               printf("can't open %s\n", argv[1]);
+               return 0;
+       }
+
+       n = read(fd, buf, BUFSIZE);
+       printf("channel_id: %d\n", atoi(buf));
+
+       options = STM_OPTION_TIMESTAMPED;
+       ioctl(fd, STM_IOCTL_SET_OPTIONS, &options);
+       options = 0;
+       ioctl(fd, STM_IOCTL_GET_OPTIONS, &options);
+       printf("options: 0x%x\n", options);
+
+       write(fd, data, strlen(data));
+
+       close(fd);
+
+       return 0;
+}
+
+When opening the devfs entry the first available channel is reserved for the
+requesting application.  That channel will remain the same until close() is
+called where it will go back to the channel pool.  From there calling open()
+again may or may _not_ yield the same channel number.
+
+From user space applications can determine what channel they've been given by
+issueing a read() on the file descriptor returned by open().  An ioctl() call 
is
+provided to set the channel options and the write() method will inject logging
+information in the channel.  There is no limit on the amount of channels an
+application can reserve, granted they use a different file descriptor for each
+one.
+
+If no more channels are available value of returned channel ID is '-1'.
+
+[1]. Documentation/ABI/testing/sysfs-bus-coresight-devices-stm
diff --git a/drivers/coresight/Kconfig b/drivers/coresight/Kconfig
index fc1f1ae7a49d..c865dcd306cd 100644
--- a/drivers/coresight/Kconfig
+++ b/drivers/coresight/Kconfig
@@ -58,4 +58,14 @@ config CORESIGHT_SOURCE_ETM3X
          which allows tracing the instructions that a processor is executing
          This is primarily useful for instruction level tracing.  Depending
          the ETM version data tracing may also be available.
+
+config CORESIGHT_STM
+       bool "CoreSight System Trace Macrocell driver"
+       depends on (ARM && !(CPU_32v3 || CPU_32v4 || CPU_32v4T)) || ARM64
+       select CORESIGHT_LINKS_AND_SINKS
+       help
+         This driver provides support for hardware assisted software
+         instrumentation based tracing. This is primarily used for
+         logging useful software events or data coming from various entities
+         in the system, possibly running different OSs
 endif
diff --git a/drivers/coresight/Makefile b/drivers/coresight/Makefile
index 4b4bec890ef5..7005b48a33ed 100644
--- a/drivers/coresight/Makefile
+++ b/drivers/coresight/Makefile
@@ -9,3 +9,4 @@ obj-$(CONFIG_CORESIGHT_SINK_ETBV10) += coresight-etb10.o
 obj-$(CONFIG_CORESIGHT_LINKS_AND_SINKS) += coresight-funnel.o \
                                           coresight-replicator.o
 obj-$(CONFIG_CORESIGHT_SOURCE_ETM3X) += coresight-etm3x.o coresight-etm-cp14.o
+obj-$(CONFIG_CORESIGHT_STM) += coresight-stm.o
diff --git a/drivers/coresight/coresight-stm.c 
b/drivers/coresight/coresight-stm.c
new file mode 100644
index 000000000000..328d67ddc2a1
--- /dev/null
+++ b/drivers/coresight/coresight-stm.c
@@ -0,0 +1,1070 @@
+/* Copyright (c) 2014-2015, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/err.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/uaccess.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/clk.h>
+#include <linux/bitmap.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/coresight.h>
+#include <linux/coresight-stm.h>
+#include <linux/amba/bus.h>
+#include <asm/unaligned.h>
+
+#include "coresight-priv.h"
+
+#define STMDMASTARTR                   0xc04
+#define STMDMASTOPR                    0xc08
+#define STMDMASTATR                    0xc0c
+#define STMDMACTLR                     0xc10
+#define STMDMAIDR                      0xcfc
+#define STMHEER                                0xd00
+#define STMHETER                       0xd20
+#define STMHEBSR                       0xd60
+#define STMHEMCR                       0xd64
+#define STMHEMASTR                     0xdf4
+#define STMHEFEAT1R                    0xdf8
+#define STMHEIDR                       0xdfc
+#define STMSPER                                0xe00
+#define STMSPTER                       0xe20
+#define STMPRIVMASKR                   0xe40
+#define STMSPSCR                       0xe60
+#define STMSPMSCR                      0xe64
+#define STMSPOVERRIDER                 0xe68
+#define STMSPMOVERRIDER                        0xe6c
+#define STMSPTRIGCSR                   0xe70
+#define STMTCSR                                0xe80
+#define STMTSSTIMR                     0xe84
+#define STMTSFREQR                     0xe8c
+#define STMSYNCR                       0xe90
+#define STMAUXCR                       0xe94
+#define STMSPFEAT1R                    0xea0
+#define STMSPFEAT2R                    0xea4
+#define STMSPFEAT3R                    0xea8
+#define STMITTRIGGER                   0xee8
+#define STMITATBDATA0                  0xeec
+#define STMITATBCTR2                   0xef0
+#define STMITATBID                     0xef4
+#define STMITATBCTR0                   0xef8
+
+#define STM_32_CHANNEL                 32
+#define BYTES_PER_CHANNEL              256
+#define STM_TRACE_BUF_SIZE             4096
+
+/* Register bit definition */
+#define STMTCSR_BUSY_BIT               23
+/* Reserve the first 10 channels for kernel usage */
+#define STM_CHANNEL_OFFSET             0
+
+enum stm_pkt_type {
+       STM_PKT_TYPE_DATA       = 0x98,
+       STM_PKT_TYPE_FLAG       = 0xE8,
+       STM_PKT_TYPE_TRIG       = 0xF8,
+};
+
+enum {
+       STM_OPTION_MARKED       = 0x10,
+};
+
+#define stm_channel_addr(drvdata, ch)  (drvdata->chs.base +    \
+                                       (ch * BYTES_PER_CHANNEL))
+#define stm_channel_off(type, opts)    (type & ~opts)
+
+#ifndef CONFIG_64BIT
+static inline void __raw_writeq(u64 val, volatile void __iomem *addr)
+{
+       asm volatile("strd %1, %0"
+                    : "+Qo" (*(volatile u64 __force *)addr)
+                    : "r" (val));
+}
+#undef writeq_relaxed
+#define writeq_relaxed(v, c)   __raw_writeq((__force u64) cpu_to_le64(v), c)
+#endif
+
+static int boot_nr_channel;
+
+module_param_named(
+       boot_nr_channel, boot_nr_channel, int, S_IRUGO
+);
+
+/**
+ * struct channel_space - central management entity for extended ports
+ * @base:              memory mapped base address where channels start.
+ * @bitmap:            tally of which channel is being used.
+ */
+struct channel_space {
+       void __iomem            *base;
+       unsigned long           *bitmap;
+};
+
+/**
+ * struct stm_node - aggregation of channel information for userspace access
+ * @channel_id:                the channel number associated to this file 
descriptor.
+ * @options:           options for this channel - none, timestamped,
+ *                     guaranteed.
+ * @drvdata:           STM driver specifics.
+ */
+struct stm_node {
+       int                     channel_id;
+       u32                     options;
+       struct stm_drvdata      *drvdata;
+};
+
+/**
+ * struct stm_drvdata - specifics associated to an STM component
+ * @ base:             memory mapped base address for this component.
+ * @dev:               the device entity associated to this component.
+ * @csdev:             component vitals needed by the framework.
+ * @miscdev:           specifics to handle "/dev/xyz.stm" entry.
+ * @clk:               the clock this component is associated to.
+ * @spinlock:          only one at a time pls.
+ * @chs:               the channels accociated to this STM.
+ * @enable:            this STM is being used.
+ * @entities:          set of entities allowed to access the STM ports.
+ * @traceid:           value of the current ID for this component.
+ * @write_64bit:       whether this STM supports 64 bit access.
+ * @stmsper:           settings for register STMSPER.
+ * @stmspscr:          settings for register STMSPSCR.
+ * @numsp:             the total number of stimulus port support by this STM.
+ * @stmheer:           settings for register STMHEER.
+ * @stmheter:          settings for register STMHETER.
+ * @stmhebsr:          settings for register STMHEBSR.
+ */
+struct stm_drvdata {
+       void __iomem            *base;
+       struct device           *dev;
+       struct coresight_device *csdev;
+       struct miscdevice       miscdev;
+       struct clk              *clk;
+       spinlock_t              spinlock;
+       struct channel_space    chs;
+       bool                    enable;
+       DECLARE_BITMAP(entities, STM_ENTITY_MAX);
+       u8                      traceid;
+       u32                     write_64bit;
+       u32                     stmsper;
+       u32                     stmspscr;
+       u32                     numsp;
+       u32                     stmheer;
+       u32                     stmheter;
+       u32                     stmhebsr;
+};
+
+static struct stm_drvdata *stmdrvdata;
+
+static void stm_hwevent_enable_hw(struct stm_drvdata *drvdata)
+{
+       CS_UNLOCK(drvdata->base);
+
+       writel_relaxed(drvdata->stmhebsr, drvdata->base + STMHEBSR);
+       writel_relaxed(drvdata->stmheter, drvdata->base + STMHETER);
+       writel_relaxed(drvdata->stmheer, drvdata->base + STMHEER);
+       writel_relaxed(0x01 |   /* Enable HW event tracing */
+                      0x04,    /* Error detection on event tracing */
+                      drvdata->base + STMHEMCR);
+
+       CS_LOCK(drvdata->base);
+}
+
+static void stm_port_enable_hw(struct stm_drvdata *drvdata)
+{
+       CS_UNLOCK(drvdata->base);
+       /* ATB trigger enable on direct writes to TRIG locations */
+       writel_relaxed(0x10,
+                      drvdata->base + STMSPTRIGCSR);
+       writel_relaxed(drvdata->stmspscr, drvdata->base + STMSPSCR);
+       writel_relaxed(drvdata->stmsper, drvdata->base + STMSPER);
+
+       CS_LOCK(drvdata->base);
+}
+
+static void stm_enable_hw(struct stm_drvdata *drvdata)
+{
+       if (drvdata->stmheer)
+               stm_hwevent_enable_hw(drvdata);
+
+       stm_port_enable_hw(drvdata);
+
+       CS_UNLOCK(drvdata->base);
+
+       /* 4096 byte between synchronisation packets */
+       writel_relaxed(0xFFF, drvdata->base + STMSYNCR);
+       writel_relaxed((drvdata->traceid << 16 | /* trace id */
+                       0x02 |                   /* timestamp enable */
+                       0x01),                   /* global STM enable */
+                       drvdata->base + STMTCSR);
+
+       CS_LOCK(drvdata->base);
+}
+
+static int stm_enable(struct coresight_device *csdev)
+{
+       struct stm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+       int ret;
+
+       ret = clk_prepare_enable(drvdata->clk);
+       if (ret)
+               return ret;
+
+       spin_lock(&drvdata->spinlock);
+       stm_enable_hw(drvdata);
+       drvdata->enable = true;
+       spin_unlock(&drvdata->spinlock);
+
+       dev_info(drvdata->dev, "STM tracing enabled\n");
+       return 0;
+}
+
+static void stm_hwevent_disable_hw(struct stm_drvdata *drvdata)
+{
+       CS_UNLOCK(drvdata->base);
+
+       writel_relaxed(0x0, drvdata->base + STMHEMCR);
+       writel_relaxed(0x0, drvdata->base + STMHEER);
+       writel_relaxed(0x0, drvdata->base + STMHETER);
+
+       CS_LOCK(drvdata->base);
+}
+
+static void stm_port_disable_hw(struct stm_drvdata *drvdata)
+{
+       CS_UNLOCK(drvdata->base);
+
+       writel_relaxed(0x0, drvdata->base + STMSPER);
+       writel_relaxed(0x0, drvdata->base + STMSPTRIGCSR);
+
+       CS_LOCK(drvdata->base);
+}
+
+static void stm_disable_hw(struct stm_drvdata *drvdata)
+{
+       u32 val;
+
+       CS_UNLOCK(drvdata->base);
+
+       val = readl_relaxed(drvdata->base + STMTCSR);
+       val &= ~0x1; /* clear global STM enable [0] */
+       writel_relaxed(val, drvdata->base + STMTCSR);
+
+       CS_LOCK(drvdata->base);
+
+       stm_port_disable_hw(drvdata);
+       if (drvdata->stmheer)
+               stm_hwevent_disable_hw(drvdata);
+}
+
+static void stm_disable(struct coresight_device *csdev)
+{
+       struct stm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+       spin_lock(&drvdata->spinlock);
+       stm_disable_hw(drvdata);
+       drvdata->enable = false;
+       spin_unlock(&drvdata->spinlock);
+
+       /* Wait until the engine has completely stopped */
+       coresight_timeout(drvdata, STMTCSR, STMTCSR_BUSY_BIT, 0);
+
+       clk_disable_unprepare(drvdata->clk);
+
+       dev_info(drvdata->dev, "STM tracing disabled\n");
+}
+
+static int stm_trace_id(struct coresight_device *csdev)
+{
+       struct stm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+       return drvdata->traceid;
+}
+
+static const struct coresight_ops_source stm_source_ops = {
+       .trace_id       = stm_trace_id,
+       .enable         = stm_enable,
+       .disable        = stm_disable,
+};
+
+static const struct coresight_ops stm_cs_ops = {
+       .source_ops     = &stm_source_ops,
+};
+
+static int stm_channel_alloc(u32 off)
+{
+       struct stm_drvdata *drvdata = stmdrvdata;
+       int ch = -1;
+
+       do {
+               ch = find_next_zero_bit(drvdata->chs.bitmap,
+                                       drvdata->numsp, off);
+       } while ((ch < drvdata->numsp) &&
+                test_and_set_bit(ch, drvdata->chs.bitmap));
+
+       return ch;
+}
+
+static void stm_channel_free(u32 ch)
+{
+       struct stm_drvdata *drvdata = stmdrvdata;
+
+       clear_bit(ch, drvdata->chs.bitmap);
+}
+
+static int stm_send_64bit(void *addr, const void *data, u32 size)
+{
+       u64 prepad = 0;
+       u64 postpad = 0;
+       char *pad;
+       u8 off, endoff;
+       u32 len = size;
+
+       off = (unsigned long)data & 0x7;
+
+       if (off) {
+               endoff = 8 - off;
+               pad = (char *)&prepad;
+               pad += off;
+
+               while (endoff && size) {
+                       *pad++ = *(char *)data++;
+                       endoff--;
+                       size--;
+               }
+               writeq_relaxed(prepad, addr);
+       }
+
+       /* now we are 64bit aligned */
+       while (size >= 8) {
+               writeq_relaxed(*(u64 *)data, addr);
+               data += 8;
+               size -= 8;
+       }
+
+       endoff = 0;
+
+       if (size) {
+               endoff = 8 - (u8)size;
+               pad = (char *)&postpad;
+
+               while (size) {
+                       *pad++ = *(char *)data++;
+                       size--;
+               }
+               writeq_relaxed(postpad, addr);
+       }
+
+       return len + off + endoff;
+}
+
+static int stm_trace_data_64bit(unsigned long ch_addr, u32 options,
+                               const void *data, u32 size)
+{
+       void *addr;
+
+       options &= ~STM_OPTION_TIMESTAMPED;
+       addr = (void *)(ch_addr | stm_channel_off(STM_PKT_TYPE_DATA, options));
+
+       return stm_send_64bit(addr, data, size);
+}
+
+static int stm_send(void *addr, const void *data, u32 size)
+{
+       u32 len = size;
+
+       if (((unsigned long)data & 0x1) && (size >= 1)) {
+               writeb_relaxed(*(u8 *)data, addr);
+               data++;
+               size--;
+       }
+       if (((unsigned long)data & 0x2) && (size >= 2)) {
+               writew_relaxed(*(u16 *)data, addr);
+               data += 2;
+               size -= 2;
+       }
+
+       /* now we are 32bit aligned */
+       while (size >= 4) {
+               writel_relaxed(*(u32 *)data, addr);
+               data += 4;
+               size -= 4;
+       }
+
+       if (size >= 2) {
+               writew_relaxed(*(u16 *)data, addr);
+               data += 2;
+               size -= 2;
+       }
+       if (size >= 1) {
+               writeb_relaxed(*(u8 *)data, addr);
+               data++;
+               size--;
+       }
+
+       return len;
+}
+
+static int stm_trace_data(unsigned long ch_addr, u32 options,
+                         const void *data, u32 size)
+{
+       void *addr;
+
+       options &= ~STM_OPTION_TIMESTAMPED;
+       addr = (void *)(ch_addr | stm_channel_off(STM_PKT_TYPE_DATA, options));
+
+       return stm_send(addr, data, size);
+}
+
+static inline int stm_trace_hw(u32 options, u32 channel, u8 entity_id,
+                              const void *data, u32 size)
+{
+       int len = 0;
+       unsigned long ch_addr;
+       struct stm_drvdata *drvdata = stmdrvdata;
+
+
+       /* get the channel address */
+       ch_addr = (unsigned long)stm_channel_addr(drvdata, channel);
+
+       if (drvdata->write_64bit)
+               len = stm_trace_data_64bit(ch_addr, options, data, size);
+       else
+               /* send the payload data */
+               len = stm_trace_data(ch_addr, options, data, size);
+
+       return len;
+}
+
+/**
+ * stm_trace - trace the binary or string data through STM
+ * @options: tracing options - guaranteed, timestamped, etc
+ * @entity_id: entity representing the trace data
+ * @data: pointer to binary r string data buffer
+ * @size: size of data to send
+ *
+ * Returns: number of bytes transferred over STM
+ */
+int stm_trace(u32 options, int channel_id,
+             u8 entity_id, const void *data, u32 size)
+{
+       struct stm_drvdata *drvdata = stmdrvdata;
+
+       if (channel_id < 0)
+               return 0;
+
+       if (!(drvdata && drvdata->enable &&
+             test_bit(entity_id, drvdata->entities)))
+               return 0;
+
+       return stm_trace_hw(options, (u32)channel_id,
+                           entity_id, data, size);
+}
+EXPORT_SYMBOL(stm_trace);
+
+static int stm_open(struct inode *inode, struct file *file)
+{
+       struct stm_node *node;
+       struct stm_drvdata *drvdata = container_of(file->private_data,
+                                                  struct stm_drvdata, miscdev);
+
+       node = kmalloc(sizeof(struct stm_node), GFP_KERNEL);
+       if (!node)
+               return -ENOMEM;
+
+       node->drvdata = drvdata;
+       node->options = STM_OPTION_TIMESTAMPED;
+       node->channel_id = stm_channel_alloc(STM_CHANNEL_OFFSET);
+       if (node->channel_id < 0)
+               return -ENOMEM;
+
+       file->private_data = node;
+       return 0;
+}
+
+static int stm_release(struct inode *inode, struct file *file)
+{
+       struct stm_node *node = file->private_data;
+
+       /* we are done, free the channel */
+       if (node->channel_id >= 0)
+               stm_channel_free((u32)node->channel_id);
+       file->private_data = NULL;
+       kfree(node);
+       return 0;
+}
+
+static ssize_t stm_read(struct file *file, char __user *data,
+                       size_t size, loff_t *ppos)
+{
+       char buf[20];
+       struct stm_node *node = file->private_data;
+
+       snprintf(buf, sizeof(buf), "%d", node->channel_id);
+       return simple_read_from_buffer(data, size, ppos,
+                                      buf, strlen(buf));
+}
+
+static ssize_t stm_write(struct file *file, const char __user *data,
+                        size_t size, loff_t *ppos)
+{
+       char *buf;
+       struct stm_node *node = file->private_data;
+       struct stm_drvdata *drvdata = node->drvdata;
+
+       if (node->channel_id < 0)
+               return -EINVAL;
+
+       if (!drvdata->enable || !size)
+               return -EINVAL;
+
+       if (size > STM_TRACE_BUF_SIZE)
+               size = STM_TRACE_BUF_SIZE;
+
+       buf = kmalloc(size, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+
+       if (copy_from_user(buf, data, size)) {
+               kfree(buf);
+               dev_dbg(drvdata->dev, "%s: copy_from_user failed\n", __func__);
+               return -EFAULT;
+       }
+
+       if (!test_bit(STM_ENTITY_TRACE_USPACE, drvdata->entities)) {
+               kfree(buf);
+               return size;
+       }
+
+       stm_trace_hw(node->options, (u32)node->channel_id,
+                    STM_ENTITY_TRACE_USPACE, buf, size);
+
+       kfree(buf);
+
+       return size;
+}
+
+static long stm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+       u32 options;
+       struct stm_node *node = file->private_data;
+
+       switch (cmd) {
+       case STM_IOCTL_SET_OPTIONS:
+               if (copy_from_user(&options, (void __user *)arg, sizeof(u32)))
+                       return -EFAULT;
+
+               options &= (STM_OPTION_TIMESTAMPED | STM_OPTION_GUARANTEED);
+               node->options = options;
+               break;
+       case STM_IOCTL_GET_OPTIONS:
+               options = node->options;
+               if (copy_to_user((void __user *)arg, &options, sizeof(options)))
+                       return -EFAULT;
+               break;
+       default:
+               return -EINVAL;
+       };
+
+       return 0;
+}
+
+static const struct file_operations stm_fops = {
+       .owner          = THIS_MODULE,
+       .open           = stm_open,
+       .write          = stm_write,
+       .read           = stm_read,
+       .llseek         = no_llseek,
+       .unlocked_ioctl = stm_ioctl,
+       .release        = stm_release,
+};
+
+static ssize_t hwevent_enable_show(struct device *dev,
+                                  struct device_attribute *attr, char *buf)
+{
+       struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+       unsigned long val = drvdata->stmheer;
+
+       return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
+}
+
+static ssize_t hwevent_enable_store(struct device *dev,
+                                   struct device_attribute *attr,
+                                   const char *buf, size_t size)
+{
+       struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+       unsigned long val;
+       int ret = 0;
+
+       ret = kstrtoul(buf, 16, &val);
+       if (ret)
+               return -EINVAL;
+
+       drvdata->stmheer = val;
+       /* HW event enable and trigger go hand in hand */
+       drvdata->stmheter = val;
+
+       return size;
+}
+static DEVICE_ATTR_RW(hwevent_enable);
+
+static ssize_t hwevent_select_show(struct device *dev,
+                                  struct device_attribute *attr, char *buf)
+{
+       struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+       unsigned long val = drvdata->stmhebsr;
+
+       return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
+}
+
+static ssize_t hwevent_select_store(struct device *dev,
+                                   struct device_attribute *attr,
+                                   const char *buf, size_t size)
+{
+       struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+       unsigned long val;
+       int ret = 0;
+
+       ret = kstrtoul(buf, 16, &val);
+       if (ret)
+               return -EINVAL;
+
+       drvdata->stmhebsr = val;
+
+       return size;
+}
+static DEVICE_ATTR_RW(hwevent_select);
+
+static ssize_t port_select_show(struct device *dev,
+                               struct device_attribute *attr, char *buf)
+{
+       struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+       unsigned long val;
+
+       if (!drvdata->enable) {
+               val = drvdata->stmspscr;
+       } else {
+               spin_lock(&drvdata->spinlock);
+               val = readl_relaxed(drvdata->base + STMSPSCR);
+               spin_unlock(&drvdata->spinlock);
+       }
+
+       return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
+}
+
+static ssize_t port_select_store(struct device *dev,
+                                struct device_attribute *attr,
+                                const char *buf, size_t size)
+{
+       struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+       unsigned long val, stmsper;
+       int ret = 0;
+
+       ret = kstrtoul(buf, 16, &val);
+       if (ret)
+               return ret;
+
+       spin_lock(&drvdata->spinlock);
+       drvdata->stmspscr = val;
+
+       if (drvdata->enable) {
+               CS_UNLOCK(drvdata->base);
+               /* Process as per ARM's TRM recommendation */
+               stmsper = readl_relaxed(drvdata->base + STMSPER);
+               writel_relaxed(0x0, drvdata->base + STMSPER);
+               writel_relaxed(drvdata->stmspscr, drvdata->base + STMSPSCR);
+               writel_relaxed(stmsper, drvdata->base + STMSPER);
+               CS_LOCK(drvdata->base);
+       }
+       spin_unlock(&drvdata->spinlock);
+
+       return size;
+}
+static DEVICE_ATTR_RW(port_select);
+
+static ssize_t port_enable_show(struct device *dev,
+                               struct device_attribute *attr, char *buf)
+{
+       struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+       unsigned long val;
+
+       if (!drvdata->enable) {
+               val = drvdata->stmsper;
+       } else {
+               spin_lock(&drvdata->spinlock);
+               val = readl_relaxed(drvdata->base + STMSPER);
+               spin_unlock(&drvdata->spinlock);
+       }
+
+       return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
+}
+
+static ssize_t port_enable_store(struct device *dev,
+                                struct device_attribute *attr,
+                                const char *buf, size_t size)
+{
+       struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+       unsigned long val;
+       int ret = 0;
+
+       ret = kstrtoul(buf, 16, &val);
+       if (ret)
+               return ret;
+
+       spin_lock(&drvdata->spinlock);
+       drvdata->stmsper = val;
+
+       if (drvdata->enable) {
+               CS_UNLOCK(drvdata->base);
+               writel_relaxed(drvdata->stmsper, drvdata->base + STMSPER);
+               CS_LOCK(drvdata->base);
+       }
+       spin_unlock(&drvdata->spinlock);
+
+       return size;
+}
+static DEVICE_ATTR_RW(port_enable);
+
+static ssize_t entities_show(struct device *dev,
+                            struct device_attribute *attr, char *buf)
+{
+       struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+       ssize_t len;
+
+       len = scnprintf(buf, PAGE_SIZE, "%*pb",
+                       STM_ENTITY_MAX, drvdata->entities);
+
+       if (PAGE_SIZE - len < 2)
+               len = -EINVAL;
+       else
+               len += scnprintf(buf + len, 2, "\n");
+
+       return len;
+}
+
+static ssize_t entities_store(struct device *dev,
+                             struct device_attribute *attr,
+                             const char *buf, size_t size)
+{
+       struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+       unsigned long val1, val2;
+
+       if (sscanf(buf, "%lx %lx", &val1, &val2) != 2)
+               return -EINVAL;
+
+       if (val1 >= STM_ENTITY_MAX)
+               return -EINVAL;
+
+       if (val2)
+               __set_bit(val1, drvdata->entities);
+       else
+               __clear_bit(val1, drvdata->entities);
+
+       return size;
+}
+static DEVICE_ATTR_RW(entities);
+
+static ssize_t status_show(struct device *dev,
+                          struct device_attribute *attr, char *buf)
+{
+       int ret;
+       unsigned long flags;
+       struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+
+       ret = clk_prepare_enable(drvdata->clk);
+       if (ret)
+               return ret;
+
+       spin_lock_irqsave(&drvdata->spinlock, flags);
+
+       CS_UNLOCK(drvdata->base);
+       ret = sprintf(buf,
+                     "STMTCSR:\t0x%08x\n"
+                     "STMTSFREQR:\t0x%08x\n"
+                     "STMTSYNCR:\t0x%08x\n"
+                     "STMSPER:\t0x%08x\n"
+                     "STMSPTER:\t0x%08x\n"
+                     "STMPRIVMASKR:\t0x%08x\n"
+                     "STMSPSCR:\t0x%08x\n"
+                     "STMSPMSCR:\t0x%08x\n"
+                     "STMFEAT1R:\t0x%08x\n"
+                     "STMFEAT2R:\t0x%08x\n"
+                     "STMFEAT3R:\t0x%08x\n"
+                     "STMDEVID:\t0x%08x\n",
+                     readl_relaxed(drvdata->base + STMTCSR),
+                     readl_relaxed(drvdata->base + STMTSFREQR),
+                     readl_relaxed(drvdata->base + STMSYNCR),
+                     readl_relaxed(drvdata->base + STMSPER),
+                     readl_relaxed(drvdata->base + STMSPTER),
+                     readl_relaxed(drvdata->base + STMPRIVMASKR),
+                     readl_relaxed(drvdata->base + STMSPSCR),
+                     readl_relaxed(drvdata->base + STMSPMSCR),
+                     readl_relaxed(drvdata->base + STMSPFEAT1R),
+                     readl_relaxed(drvdata->base + STMSPFEAT2R),
+                     readl_relaxed(drvdata->base + STMSPFEAT3R),
+                     readl_relaxed(drvdata->base + CORESIGHT_DEVID));
+
+       CS_LOCK(drvdata->base);
+       spin_unlock_irqrestore(&drvdata->spinlock, flags);
+       clk_disable_unprepare(drvdata->clk);
+
+       return ret;
+}
+static DEVICE_ATTR_RO(status);
+
+static ssize_t traceid_show(struct device *dev,
+                           struct device_attribute *attr, char *buf)
+{
+       unsigned long val;
+       struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+
+       val = drvdata->traceid;
+       return sprintf(buf, "%#lx\n", val);
+}
+
+static ssize_t traceid_store(struct device *dev,
+                            struct device_attribute *attr,
+                            const char *buf, size_t size)
+{
+       int ret;
+       unsigned long val;
+       struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+
+       ret = kstrtoul(buf, 16, &val);
+       if (ret)
+               return ret;
+
+       /* traceid field is 7bit wide on STM32 */
+       drvdata->traceid = val & 0x7f;
+       return size;
+}
+static DEVICE_ATTR_RW(traceid);
+
+static struct attribute *coresight_stm_attrs[] = {
+       &dev_attr_hwevent_enable.attr,
+       &dev_attr_hwevent_select.attr,
+       &dev_attr_port_enable.attr,
+       &dev_attr_port_select.attr,
+       &dev_attr_entities.attr,
+       &dev_attr_status.attr,
+       &dev_attr_traceid.attr,
+       NULL,
+};
+ATTRIBUTE_GROUPS(coresight_stm);
+
+static int stm_get_resource_byname(struct device_node *np,
+                                  char *ch_base, struct resource *res)
+{
+       const char *name = NULL;
+       int index = 0, found = 0;
+
+       while (!of_property_read_string_index(np, "reg-names", index, &name)) {
+               if (strcmp(ch_base, name)) {
+                       index++;
+                       continue;
+               }
+
+               /* We have a match and @index is where it's at */
+               found = 1;
+               break;
+       }
+
+       if (!found)
+               return -EINVAL;
+
+       return of_address_to_resource(np, index, res);
+}
+
+static u32 stm_fundamental_data_size(struct stm_drvdata *drvdata)
+{
+       u32 stmspfeat2r;
+
+       stmspfeat2r = readl_relaxed(drvdata->base + STMSPFEAT2R);
+       return BMVAL(stmspfeat2r, 12, 15);
+}
+
+static u32 stm_num_stimulus_port(struct stm_drvdata *drvdata)
+{
+       u32 numsp;
+
+       numsp = readl_relaxed(drvdata->base + CORESIGHT_DEVID);
+       /*
+        * NUMPS in STMDEVID is 17 bit long and if equal to 0x0,
+        * 32 stimulus ports are supported.
+        */
+       numsp &= 0x1ffff;
+       if (!numsp)
+               numsp = STM_32_CHANNEL;
+       return numsp;
+}
+
+static void stm_init_default_data(struct stm_drvdata *drvdata)
+{
+       /* Don't use port selection */
+       drvdata->stmspscr = 0x0;
+       /*
+        * Enable all channel regardless of their number.  When port
+        * selection isn't used (see above) STMSPER applies to all
+        * 32 channel group available, hence setting all 32 bits to 1
+        */
+       drvdata->stmsper = ~0x0;
+
+       /*
+        * Select arbitrary value to start with.  If there is a conflict
+        * with other tracers the framework will deal with it.
+        */
+       drvdata->traceid = 0x20;
+
+       bitmap_zero(drvdata->entities, STM_ENTITY_MAX);
+}
+
+static int stm_probe(struct amba_device *adev, const struct amba_id *id)
+{
+       int ret;
+       void __iomem *base;
+       unsigned long *bitmap;
+       struct device *dev = &adev->dev;
+       struct coresight_platform_data *pdata = NULL;
+       struct stm_drvdata *drvdata;
+       struct resource *res = &adev->res;
+       struct resource ch_res;
+       size_t res_size, bitmap_size;
+       struct coresight_desc *desc;
+       struct device_node *np = adev->dev.of_node;
+
+       if (np) {
+               pdata = of_get_coresight_platform_data(dev, np);
+               if (IS_ERR(pdata))
+                       return PTR_ERR(pdata);
+               adev->dev.platform_data = pdata;
+       }
+       drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
+       if (!drvdata)
+               return -ENOMEM;
+
+       /* Store the driver data pointer for use in exported functions */
+       stmdrvdata = drvdata;
+       drvdata->dev = &adev->dev;
+       dev_set_drvdata(dev, drvdata);
+
+       base = devm_ioremap_resource(dev, res);
+       if (IS_ERR(base))
+               return PTR_ERR(base);
+       drvdata->base = base;
+
+       ret = stm_get_resource_byname(np, "stm-channel-base", &ch_res);
+       if (ret)
+               return ret;
+
+       base = devm_ioremap_resource(dev, &ch_res);
+       if (IS_ERR(base))
+               return PTR_ERR(base);
+       drvdata->chs.base = base;
+
+       ret = clk_prepare_enable(drvdata->clk);
+       if (ret)
+               return ret;
+
+       drvdata->write_64bit = stm_fundamental_data_size(drvdata);
+
+       if (boot_nr_channel) {
+               drvdata->numsp = boot_nr_channel;
+               res_size = min((resource_size_t)(boot_nr_channel *
+                                 BYTES_PER_CHANNEL), resource_size(res));
+               bitmap_size = boot_nr_channel * sizeof(long);
+       } else {
+               drvdata->numsp = stm_num_stimulus_port(drvdata);
+               res_size = min((resource_size_t)(drvdata->numsp *
+                                BYTES_PER_CHANNEL), resource_size(res));
+               bitmap_size = drvdata->numsp * sizeof(long);
+       }
+
+       clk_disable_unprepare(drvdata->clk);
+
+       bitmap = devm_kzalloc(dev, bitmap_size, GFP_KERNEL);
+       if (!bitmap)
+               return -ENOMEM;
+       drvdata->chs.bitmap = bitmap;
+
+       spin_lock_init(&drvdata->spinlock);
+
+       drvdata->clk = adev->pclk;
+
+       stm_init_default_data(drvdata);
+
+       desc = devm_kzalloc(dev, sizeof(*desc), GFP_KERNEL);
+       if (!desc)
+               return -ENOMEM;
+
+       desc->type = CORESIGHT_DEV_TYPE_SOURCE;
+       desc->subtype.source_subtype = CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE;
+       desc->ops = &stm_cs_ops;
+       desc->pdata = pdata;
+       desc->dev = dev;
+       desc->groups = coresight_stm_groups;
+       drvdata->csdev = coresight_register(desc);
+       if (IS_ERR(drvdata->csdev))
+               return PTR_ERR(drvdata->csdev);
+
+       drvdata->miscdev.name = pdata->name;
+       drvdata->miscdev.minor = MISC_DYNAMIC_MINOR;
+       drvdata->miscdev.fops = &stm_fops;
+       ret = misc_register(&drvdata->miscdev);
+       if (ret)
+               goto err;
+
+       dev_info(drvdata->dev, "STM initialized\n");
+
+       return 0;
+err:
+       coresight_unregister(drvdata->csdev);
+       return ret;
+}
+
+static int stm_remove(struct amba_device *adev)
+{
+       struct stm_drvdata *drvdata = amba_get_drvdata(adev);
+
+       misc_deregister(&drvdata->miscdev);
+       coresight_unregister(drvdata->csdev);
+       return 0;
+}
+
+static struct amba_id stm_ids[] = {
+       {
+               .id     = 0x0003b962,
+               .mask   = 0x0003ffff,
+       },
+       { 0, 0},
+};
+
+static struct amba_driver stm_driver = {
+       .drv = {
+               .name   = "coresight-stm",
+               .owner  = THIS_MODULE,
+       },
+       .probe          = stm_probe,
+       .remove         = stm_remove,
+       .id_table       = stm_ids,
+};
+
+module_amba_driver(stm_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("CoreSight System Trace Macrocell driver");
diff --git a/include/linux/coresight-stm.h b/include/linux/coresight-stm.h
new file mode 100644
index 000000000000..fc791562ad7c
--- /dev/null
+++ b/include/linux/coresight-stm.h
@@ -0,0 +1,40 @@
+#ifndef __LINUX_CORESIGHT_STM_H_
+#define __LINUX_CORESIGHT_STM_H_
+
+#include <uapi/linux/coresight-stm.h>
+
+/* kernel uses ch_id 0 until a better (more flexible) way is found */
+#define CH_ID_KERNEL   0
+
+#define stm_log_inv(entity_id, ch_id, data, size)              \
+       stm_trace(STM_OPTION_NONE, CH_ID_KERNEL,                \
+       STM_ENTITY_TRACE_KERNEL, data, size)
+
+#define stm_log_inv_ts(entity_id, ch_id, data, size)           \
+       stm_trace(STM_OPTION_TIMESTAMPED, CH_ID_KERNEL,         \
+       STM_ENTITY_TRACE_KERNEL, data, size)                    \
+
+#define stm_log_gtd(entity_id, ch_id, data, size)              \
+       stm_trace(STM_OPTION_GUARANTEED, CH_ID_KERNEL,          \
+       STM_ENTITY_TRACE_KERNEL, data, size)                    \
+
+#define stm_log_gtd_ts(entity_id, ch_id, data, size)           \
+       stm_trace(STM_OPTION_GUARANTEED |                       \
+                 STM_OPTION_TIMESTAMPED,                       \
+                 CH_ID_KERNEL, STM_ENTITY_TRACE_KERNEL, data, size)
+
+#define stm_log(entity_id, ch_id, data, size)                  \
+       stm_log_inv_ts(entity_id, ch_id, data, size)
+
+#ifdef CONFIG_CORESIGHT_STM
+extern int stm_trace(u32 options, int channel_id,
+                    u8 entity_id, const void *data, u32 size);
+#else
+static inline int stm_trace(u32 options, int channel_id,
+                           u8 entity_id, const void *data, u32 size)
+{
+       return 0;
+}
+#endif
+
+#endif
diff --git a/include/uapi/linux/coresight-stm.h 
b/include/uapi/linux/coresight-stm.h
new file mode 100644
index 000000000000..208a4d79c4ee
--- /dev/null
+++ b/include/uapi/linux/coresight-stm.h
@@ -0,0 +1,23 @@
+#ifndef __UAPI_CORESIGHT_STM_H_
+#define __UAPI_CORESIGHT_STM_H_
+
+enum {
+       STM_ENTITY_NONE                 = 0x00,
+       STM_ENTITY_TRACE_KERNEL         = 0x01,
+       STM_ENTITY_TRACE_USPACE         = 0x10,
+       STM_ENTITY_MAX                  = 0xFF,
+};
+
+enum {
+       STM_IOCTL_NONE                  = 0x00,
+       STM_IOCTL_SET_OPTIONS           = 0x01,
+       STM_IOCTL_GET_OPTIONS           = 0x10,
+};
+
+enum {
+       STM_OPTION_NONE                 = 0x0,
+       STM_OPTION_TIMESTAMPED          = 0x08,
+       STM_OPTION_GUARANTEED           = 0x80,
+};
+
+#endif
-- 
1.9.1

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