Hi Stephen,
On Mon, 15 Oct 2012 23:10:35 -0600, Stephen Warren
<swar...@wwwdotorg.org> wrote:
> The BCM2835 SoC contains (at least) two CPUs; the VideoCore (a/k/a "GPU")
> and the ARM CPU. The ARM CPU is often thought of as the main CPU.
> However, the VideoCore actually controls the initial SoC boot, and hides
> much of the hardware behind a protocol. This protocol is transported
> using the SoC's mailbox hardware module. The mailbox supports two forms
> of communication: Raw 28-bit values, and a so-called "property"
> interface, where the 28-bit value is a physical pointer to a memory
> buffer that contains various "tags".
>
> Here, we add a very simplistic driver for the mailbox module, and define
> a few structures for the property messages.
>
> Signed-off-by: Stephen Warren <swar...@wwwdotorg.org>
> ---
> arch/arm/cpu/arm1176/bcm2835/Makefile | 2 +-
> arch/arm/cpu/arm1176/bcm2835/mbox.c | 92
> ++++++++++++++++++++++++++++++
> arch/arm/include/asm/arch-bcm2835/mbox.h | 87 ++++++++++++++++++++++++++++
> 3 files changed, 180 insertions(+), 1 deletion(-)
> create mode 100644 arch/arm/cpu/arm1176/bcm2835/mbox.c
> create mode 100644 arch/arm/include/asm/arch-bcm2835/mbox.h
>
> diff --git a/arch/arm/cpu/arm1176/bcm2835/Makefile
> b/arch/arm/cpu/arm1176/bcm2835/Makefile
> index 95da6a8..135de42 100644
> --- a/arch/arm/cpu/arm1176/bcm2835/Makefile
> +++ b/arch/arm/cpu/arm1176/bcm2835/Makefile
> @@ -17,7 +17,7 @@ include $(TOPDIR)/config.mk
> LIB = $(obj)lib$(SOC).o
>
> SOBJS := lowlevel_init.o
> -COBJS := init.o reset.o timer.o
> +COBJS := init.o reset.o timer.o mbox.o
>
> SRCS := $(SOBJS:.o=.c) $(COBJS:.o=.c)
> OBJS := $(addprefix $(obj),$(SOBJS) $(COBJS))
> diff --git a/arch/arm/cpu/arm1176/bcm2835/mbox.c
> b/arch/arm/cpu/arm1176/bcm2835/mbox.c
> new file mode 100644
> index 0000000..f5c060b
> --- /dev/null
> +++ b/arch/arm/cpu/arm1176/bcm2835/mbox.c
> @@ -0,0 +1,92 @@
> +/*
> + * (C) Copyright 2012 Stephen Warren
> + *
> + * See file CREDITS for list of people who contributed to this
> + * project.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * 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 <common.h>
> +#include <asm/io.h>
> +#include <asm/arch/mbox.h>
> +
> +#define TIMEOUT (100 * 1000) /* 100mS in uS */
> +
> +int bcm2835_mbox_call_raw(u32 chan, u32 send, u32 *recv)
> +{
> + struct bcm2835_mbox_regs *regs =
> + (struct bcm2835_mbox_regs *)BCM2835_MBOX_PHYSADDR;
> + ulong endtime = get_timer(0) + TIMEOUT;
> + u32 val;
> +
> + if (send & BCM2835_CHAN_MASK)
> + return -1;
> +
> + /* Drain any stale responses */
> +
> + for (;;) {
> + val = readl(®s->status);
> + if (val & BCM2835_MBOX_STATUS_RD_EMPTY)
> + break;
> + if (get_timer(0) >= endtime)
> + return -1;
> + val = readl(®s->read);
> + }
> +
> + /* Send the request */
> +
> + /* FIXME: timeout */
Develop this FIXME to indicate what exactly should be fixed.
> + for (;;) {
> + val = readl(®s->status);
> + if (!(val & BCM2835_MBOX_STATUS_WR_FULL))
> + break;
> + if (get_timer(0) >= endtime)
> + return -1;
> + }
> +
> + writel(BCM2835_MBOX_PACK(chan, send), ®s->write);
> +
> + /* Wait for the response */
> +
> + /* FIXME: timeout */
Ditto.
> + for (;;) {
> + val = readl(®s->status);
> + if (!(val & BCM2835_MBOX_STATUS_RD_EMPTY))
> + break;
> + if (get_timer(0) >= endtime)
> + return -1;
> + }
> +
> + val = readl(®s->read);
> +
> + /* Validate the response */
> +
> + if (BCM2835_MBOX_UNPACK_CHAN(val) != chan)
> + return -1;
> +
> + *recv = BCM2835_MBOX_UNPACK_DATA(val);
> +
> + return 0;
> +}
> +
> +int bcm2835_mbox_call_prop(u32 chan, struct bcm2835_mbox_prop_hdr *buffer)
> +{
> + int ret;
> + u32 rbuffer;
> +
> + ret = bcm2835_mbox_call_raw(chan, (u32)buffer, &rbuffer);
> + if (ret)
> + return ret;
> + if (rbuffer != (u32)buffer)
> + return -1;
> +
> + return 0;
> +}
> diff --git a/arch/arm/include/asm/arch-bcm2835/mbox.h
> b/arch/arm/include/asm/arch-bcm2835/mbox.h
> new file mode 100644
> index 0000000..907fabd
> --- /dev/null
> +++ b/arch/arm/include/asm/arch-bcm2835/mbox.h
> @@ -0,0 +1,87 @@
> +/*
> + * (C) Copyright 2012 Stephen Warren
> + *
> + * See file CREDITS for list of people who contributed to this
> + * project.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * 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.
> + */
> +
> +#ifndef _BCM2835_MBOX_H
> +#define _BCM2835_MBOX_H
> +
> +#include <linux/compiler.h>
> +
> +/* Raw mailbox HW */
> +
> +#define BCM2835_MBOX_PHYSADDR 0x2000b880
> +
> +struct bcm2835_mbox_regs {
> + u32 read;
> + u32 rsvd0[5];
> + u32 status;
> + u32 config;
> + u32 write;
> +};
> +
> +#define BCM2835_MBOX_STATUS_WR_FULL 0x80000000
> +#define BCM2835_MBOX_STATUS_RD_EMPTY 0x40000000
> +
> +#define BCM2835_CHAN_MASK 0xf
> +
> +#define BCM2835_MBOX_PACK(chan, data) (((data) &
> (~BCM2835_CHAN_MASK)) | \
> + (chan & BCM2835_CHAN_MASK))
> +#define BCM2835_MBOX_UNPACK_CHAN(val) ((val) & BCM2835_CHAN_MASK)
> +#define BCM2835_MBOX_UNPACK_DATA(val) ((val) & (~BCM2835_CHAN_MASK))
> +
> +/* Property mailbox buffer structures */
> +
> +#define BCM2835_MBOX_PROP_CHAN 8
> +
> +struct bcm2835_mbox_prop_hdr {
> + u32 buf_size;
> + u32 code;
> +} __packed;
Remove __packed here, as all fields are 32 bits and thus no padding
would happen anyway.
> +#define BCM2835_MBOX_REQ_CODE 0
> +#define BCM2835_MBOX_RESP_CODE_SUCCESS 0x80000000
> +
> +struct bcm2835_mbox_tag_hdr {
> + u32 tag;
> + u32 val_buf_size;
> + u32 val_len;
> +} __packed;
Ditto.
> +#define BCM2835_MBOX_TAG_VAL_LEN_RESPONSE 0x80000000
> +
> +#define BCM2835_MBOX_TAG_GET_ARM_MEMORY 0x00010005
> +
> +struct bcm2835_mbox_req_get_arm_mem {
> +} __packed;
Ditto (for an empty struct).
> +struct bcm2835_mbox_resp_get_arm_mem {
> + u32 mem_base;
> + u32 mem_size;
> +} __packed;
Ditto.
> +struct bcm2835_mbox_buf_get_arm_mem {
> + struct bcm2835_mbox_prop_hdr hdr;
> + struct bcm2835_mbox_tag_hdr tag_hdr;
> + union {
> + struct bcm2835_mbox_req_get_arm_mem req;
> + struct bcm2835_mbox_resp_get_arm_mem resp;
> + } body;
> + u32 end_tag;
> +} __packed;
Ditto.
Also, what is the point of bcm2835_mbox_buf_get_arm_mem which is not
referenced in the API below?
> +int bcm2835_mbox_call_raw(u32 chan, u32 send, u32 *recv);
> +int bcm2835_mbox_call_prop(u32 chan, struct bcm2835_mbox_prop_hdr *buffer);
> +
> +#endif
Amicalement,
--
Albert.
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