Hi Sam,
On Wed, Dec 13, 2023 at 3:16 AM Sam Protsenko
<semen.protse...@linaro.org> wrote:
>
> USIv2 IP-core is found on modern ARM64 Exynos SoCs (like Exynos850) and
> provides selectable serial protocol (one of: UART, SPI, I2C). USIv2
> registers usually reside in the same register map as a particular
> underlying protocol it implements, but have some particular offset. E.g.
> on Exynos850 the USI_UART has 0x13820000 base address, where UART
> registers have 0x00..0x40 offsets, and USI registers have 0xc0..0xdc
> offsets. Desired protocol can be chosen via SW_CONF register from System
> Register block of the same domain as USI.
>
> Before starting to use a particular protocol, USIv2 must be configured
> properly:
> 1. Select protocol to be used via System Register
> 2. Clear "reset" flag in USI_CON
> 3. Configure HWACG behavior (e.g. for UART Rx the HWACG must be
> disabled, so that the IP clock is not gated automatically); this is
> done using USI_OPTION register
> 4. Keep both USI clocks (PCLK and IPCLK) running during USI registers
> modification
>
> This driver implements the above behavior. Of course, USIv2 driver
> should be probed before UART/I2C/SPI drivers. It can be achieved by
> embedding UART/I2C/SPI nodes inside of the USI node (in Device Tree);
> driver then walks underlying nodes and instantiates those. Driver also
> handles USI configuration on PM resume, as register contents can be lost
> during CPU suspend.
>
> This driver is designed with different USI versions in mind. So it
> should be relatively easy to add new USI revisions to it later.
>
> Driver's code was copied over from Linux kernel [1] and adapted
> correspondingly for U-Boot API. UCLASS_MISC is used, and although no
> misc operations are implemented, it makes it easier to probe the driver
> this way (as compared to UCLASS_NOP) and keep the code compact.
>
> [1] drivers/soc/samsung/exynos-usi.c
>
> Signed-off-by: Sam Protsenko <semen.protse...@linaro.org>
> ---
> drivers/soc/Kconfig | 1 +
> drivers/soc/Makefile | 1 +
> drivers/soc/samsung/Kconfig | 23 ++++
> drivers/soc/samsung/Makefile | 3 +
> drivers/soc/samsung/exynos-usi.c | 218 +++++++++++++++++++++++++++++++
> 5 files changed, 246 insertions(+)
> create mode 100644 drivers/soc/samsung/Kconfig
> create mode 100644 drivers/soc/samsung/Makefile
> create mode 100644 drivers/soc/samsung/exynos-usi.c
>
Just a few nits here
Reviewed-by: Simon Glass <s...@chromium.org>
> diff --git a/drivers/soc/Kconfig b/drivers/soc/Kconfig
> index 85dac9de78a4..03433bc0e6d2 100644
> --- a/drivers/soc/Kconfig
> +++ b/drivers/soc/Kconfig
> @@ -40,6 +40,7 @@ config SOC_XILINX_VERSAL_NET
> This allows other drivers to verify the SoC familiy & revision using
> matching SoC attributes.
>
> +source "drivers/soc/samsung/Kconfig"
> source "drivers/soc/ti/Kconfig"
>
> endmenu
> diff --git a/drivers/soc/Makefile b/drivers/soc/Makefile
> index 84385650d46d..610bf816d40a 100644
> --- a/drivers/soc/Makefile
> +++ b/drivers/soc/Makefile
> @@ -2,6 +2,7 @@
> #
> # Makefile for the U-Boot SOC specific device drivers.
>
> +obj-$(CONFIG_SOC_SAMSUNG) += samsung/
> obj-$(CONFIG_SOC_TI) += ti/
> obj-$(CONFIG_SOC_DEVICE) += soc-uclass.o
> obj-$(CONFIG_SOC_DEVICE_TI_K3) += soc_ti_k3.o
> diff --git a/drivers/soc/samsung/Kconfig b/drivers/soc/samsung/Kconfig
> new file mode 100644
> index 000000000000..ffb87fe79316
> --- /dev/null
> +++ b/drivers/soc/samsung/Kconfig
> @@ -0,0 +1,23 @@
> +# SPDX-License-Identifier: GPL-2.0+
> +
> +menuconfig SOC_SAMSUNG
> + bool "Samsung SoC drivers support"
> +
> +if SOC_SAMSUNG
> +
> +config EXYNOS_USI
> + bool "Exynos USI (Universal Serial Interface) driver"
> + depends on ARCH_EXYNOS
> + select MISC
> + select REGMAP
> + select SYSCON
> + help
> + Enable support for USI block. USI (Universal Serial Interface) is an
> + IP-core found in modern Samsung Exynos SoCs, like Exynos850 and
> + ExynosAutoV9. USI block can be configured to provide one of the
> + following serial protocols: UART, SPI or High Speed I2C.
> +
> + This driver allows one to configure USI for desired protocol, which
> + is usually done in USI node in Device Tree.
> +
> +endif
> diff --git a/drivers/soc/samsung/Makefile b/drivers/soc/samsung/Makefile
> new file mode 100644
> index 000000000000..833ac073fbfa
> --- /dev/null
> +++ b/drivers/soc/samsung/Makefile
> @@ -0,0 +1,3 @@
> +# SPDX-License-Identifier: GPL-2.0+
> +
> +obj-$(CONFIG_EXYNOS_USI) += exynos-usi.o
> diff --git a/drivers/soc/samsung/exynos-usi.c
> b/drivers/soc/samsung/exynos-usi.c
> new file mode 100644
> index 000000000000..23255177e6e3
> --- /dev/null
> +++ b/drivers/soc/samsung/exynos-usi.c
> @@ -0,0 +1,218 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2023 Linaro Ltd.
> + * Author: Sam Protsenko <semen.protse...@linaro.org>
> + *
> + * Samsung Exynos USI driver (Universal Serial Interface).
> + */
> +
> +#include <dm.h>
> +#include <dm/device_compat.h>
> +#include <errno.h>
> +#include <regmap.h>
> +#include <syscon.h>
> +#include <asm/io.h>
> +#include <linux/bitops.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +
> +#include <dt-bindings/soc/samsung,exynos-usi.h>
> +
> +/* USIv2: System Register: SW_CONF register bits */
> +#define USI_V2_SW_CONF_NONE 0x0
> +#define USI_V2_SW_CONF_UART BIT(0)
> +#define USI_V2_SW_CONF_SPI BIT(1)
> +#define USI_V2_SW_CONF_I2C BIT(2)
> +#define USI_V2_SW_CONF_MASK (USI_V2_SW_CONF_UART | USI_V2_SW_CONF_SPI | \
> + USI_V2_SW_CONF_I2C)
> +
> +/* USIv2: USI register offsets */
> +#define USI_CON 0x04
> +#define USI_OPTION 0x08
> +
> +/* USIv2: USI register bits */
> +#define USI_CON_RESET BIT(0)
> +#define USI_OPTION_CLKREQ_ON BIT(1)
> +#define USI_OPTION_CLKSTOP_ON BIT(2)
> +
> +enum exynos_usi_ver {
> + USI_VER2 = 2,
> +};
> +
> +struct exynos_usi_variant {
> + enum exynos_usi_ver ver; /* USI IP-core version */
> + unsigned int sw_conf_mask; /* SW_CONF mask for all protocols */
> + size_t min_mode; /* first index in exynos_usi_modes[]
> */
> + size_t max_mode; /* last index in exynos_usi_modes[] */
> +};
> +
> +struct exynos_usi {
> + struct udevice *dev;
Can we drop this? It doesn't seem very useful and we try to avoid
having bidirectional pointers. since it is possible to get the 'priv'
pointer from the device.
> + void __iomem *regs; /* USI register map */
> +
> + size_t mode; /* current USI SW_CONF mode index */
> + bool clkreq_on; /* always provide clock to IP */
> +
> + /* System Register */
> + struct regmap *sysreg; /* System Register map */
> + unsigned int sw_conf; /* SW_CONF register offset in sysreg
> */
> +
> + const struct exynos_usi_variant *data;
> +};
> +
> +struct exynos_usi_mode {
> + const char *name; /* mode name */
> + unsigned int val; /* mode register value */
> +};
> +
> +static const struct exynos_usi_mode exynos_usi_modes[] = {
> + [USI_V2_NONE] = { .name = "none", .val = USI_V2_SW_CONF_NONE },
> + [USI_V2_UART] = { .name = "uart", .val = USI_V2_SW_CONF_UART },
> + [USI_V2_SPI] = { .name = "spi", .val = USI_V2_SW_CONF_SPI },
> + [USI_V2_I2C] = { .name = "i2c", .val = USI_V2_SW_CONF_I2C },
> +};
> +
> +static const struct exynos_usi_variant exynos850_usi_data = {
> + .ver = USI_VER2,
> + .sw_conf_mask = USI_V2_SW_CONF_MASK,
> + .min_mode = USI_V2_NONE,
> + .max_mode = USI_V2_I2C,
> +};
> +
> +static const struct udevice_id exynos_usi_ids[] = {
> + {
> + .compatible = "samsung,exynos850-usi",
> + .data = (ulong)&exynos850_usi_data,
> + },
> + { } /* sentinel */
> +};
> +
> +/**
> + * exynos_usi_set_sw_conf - Set USI block configuration mode
> + * @usi: USI driver object
> + * @mode: Mode index
> + *
> + * Select underlying serial protocol (UART/SPI/I2C) in USI IP-core.
> + *
> + * Return: 0 on success, or negative error code on failure.
> + */
> +static int exynos_usi_set_sw_conf(struct exynos_usi *usi, size_t mode)
> +{
> + unsigned int val;
> + int ret;
> +
> + if (mode < usi->data->min_mode || mode > usi->data->max_mode)
> + return -EINVAL;
> +
> + val = exynos_usi_modes[mode].val;
> + ret = regmap_update_bits(usi->sysreg, usi->sw_conf,
> + usi->data->sw_conf_mask, val);
> + if (ret)
> + return ret;
> +
> + usi->mode = mode;
> + dev_dbg(usi->dev, "protocol: %s\n", exynos_usi_modes[usi->mode].name);
> +
> + return 0;
> +}
> +
> +/**
> + * exynos_usi_enable - Initialize USI block
> + * @usi: USI driver object
> + *
> + * USI IP-core start state is "reset" (on startup and after CPU resume). This
> + * routine enables the USI block by clearing the reset flag. It also
> configures
> + * HWACG behavior (needed e.g. for UART Rx). It should be performed before
> + * underlying protocol becomes functional.
> + */
> +static void exynos_usi_enable(const struct exynos_usi *usi)
> +{
> + u32 val;
> +
> + /* Enable USI block */
> + val = readl(usi->regs + USI_CON);
> + val &= ~USI_CON_RESET;
> + writel(val, usi->regs + USI_CON);
> + udelay(1);
> +
> + /* Continuously provide the clock to USI IP w/o gating */
> + if (usi->clkreq_on) {
> + val = readl(usi->regs + USI_OPTION);
> + val &= ~USI_OPTION_CLKSTOP_ON;
> + val |= USI_OPTION_CLKREQ_ON;
> + writel(val, usi->regs + USI_OPTION);
> + }
> +}
> +
> +static int exynos_usi_configure(struct exynos_usi *usi)
> +{
> + int ret;
> +
> + ret = exynos_usi_set_sw_conf(usi, usi->mode);
> + if (ret)
> + return ret;
> +
> + if (usi->data->ver == USI_VER2)
> + exynos_usi_enable(usi);
> +
> + return 0;
> +}
> +
> +static int exynos_usi_parse_dt(struct exynos_usi *usi)
Use of_to_plat() method?
> +{
> + struct udevice *dev = usi->dev;
> + ofnode node;
> + int ret;
> + u32 mode;
> +
> + node = dev_ofnode(dev);
> +
> + ret = ofnode_read_u32(node, "samsung,mode", &mode);
> + if (ret)
> + return ret;
> + if (mode < usi->data->min_mode || mode > usi->data->max_mode)
> + return -EINVAL;
> + usi->mode = mode;
> +
> + usi->sysreg = syscon_regmap_lookup_by_phandle(dev, "samsung,sysreg");
> + if (IS_ERR(usi->sysreg))
> + return PTR_ERR(usi->sysreg);
> +
> + ret = ofnode_read_u32_index(node, "samsung,sysreg", 1, &usi->sw_conf);
> + if (ret)
> + return ret;
> +
> + usi->clkreq_on = ofnode_read_bool(node, "samsung,clkreq-on");
> +
> + return 0;
> +}
> +
> +static int exynos_usi_probe(struct udevice *dev)
> +{
> + struct exynos_usi *usi;
> + int ret;
> +
> + usi = dev_get_priv(dev);
> + usi->dev = dev;
Hoping you can drop that
> + usi->data = (struct exynos_usi_variant *)dev_get_driver_data(dev);
> +
> + ret = exynos_usi_parse_dt(usi);
> + if (ret)
> + return ret;
> +
> + if (usi->data->ver == USI_VER2) {
> + usi->regs = dev_read_addr_ptr(dev);
> + if (!usi->regs)
> + return -ENODEV;
> + }
> +
> + return exynos_usi_configure(usi);
> +}
> +
> +U_BOOT_DRIVER(exynos_usi) = {
> + .name = "exynos-usi",
> + .id = UCLASS_MISC,
> + .of_match = exynos_usi_ids,
> + .probe = exynos_usi_probe,
> + .priv_auto = sizeof(struct exynos_usi),
> +};
> --
> 2.39.2
>
Regards,
Simon
