Re: [PATCH 3/3] soc: ti: Add TDA54 SCM configuration syscon support

[Moteen Shah <m-shah@ti.com>]

On 19/10/26 13:37, Moteen Shah wrote:
> Add the TDA54 SCM configuration driver providing access to the SCM register
> space through regmap/syscon.
>
> The driver handles proxy-based register access and SCM unlock/claim
> handling, and registers TDA54 SoC information using the common K3 SoC
> info helper exported by k3-socinfo, for which the TDA54 part number is
> added to the SoC ID table.
>
> Default the option to m on ARCH_K3, so that the driver gets built for TDA54
> boards without requiring a defconfig change.
>
> Signed-off-by: Moteen Shah <m-shah@ti.com>
> Signed-off-by: Aniket Limaye <a-limaye@ti.com>
> ---
>   drivers/soc/ti/Kconfig             |  16 +++
>   drivers/soc/ti/Makefile            |   1 +
>   drivers/soc/ti/k3-socinfo.c        |   2 +
>   drivers/soc/ti/tda54-mcu-sysconf.c | 216 +++++++++++++++++++++++++++++
>   4 files changed, 235 insertions(+)
>   create mode 100644 drivers/soc/ti/tda54-mcu-sysconf.c
>
> diff --git a/drivers/soc/ti/Kconfig b/drivers/soc/ti/Kconfig
> index 163aadd589d3a..ea5da6722da29 100644
> --- a/drivers/soc/ti/Kconfig
> +++ b/drivers/soc/ti/Kconfig
> @@ -82,6 +82,22 @@ config TI_PRUSS
>   	  processors on various TI SoCs. It's safe to say N here if you're
>   	  not interested in the PRU or if you are unsure.
>   
> +config TI_TDA54_MCU_SYSCONF
> +	tristate "TI TDA54 SCM configuration controller"
> +	depends on ARCH_K3 || COMPILE_TEST
> +	depends on OF
> +	default m if ARCH_K3
> +	select MFD_SYSCON
> +	select TI_K3_SOCINFO
> +	help
> +	  Support the SCM configuration controller found on TI TDA54.
> +	  The controller provides a syscon regmap and is also the
> +	  hardware access path used to obtain and register K3 SoC
> +	  identification information.
> +
> +	  This driver can be built as a module, in which case the module
> +	  will be called tda54-mcu-sysconf.
> +
>   endif # SOC_TI
>   
>   config TI_SCI_INTA_MSI_DOMAIN
> diff --git a/drivers/soc/ti/Makefile b/drivers/soc/ti/Makefile
> index cb800a745e66d..33f4ddca32ed6 100644
> --- a/drivers/soc/ti/Makefile
> +++ b/drivers/soc/ti/Makefile
> @@ -11,4 +11,5 @@ obj-$(CONFIG_TI_SCI_INTA_MSI_DOMAIN)	+= ti_sci_inta_msi.o
>   obj-$(CONFIG_TI_K3_RINGACC)		+= k3-ringacc.o
>   obj-$(CONFIG_TI_K3_SOCINFO)		+= k3-socinfo.o
>   obj-$(CONFIG_TI_PRUSS)			+= pruss.o
> +obj-$(CONFIG_TI_TDA54_MCU_SYSCONF)	+= tda54-mcu-sysconf.o
>   obj-$(CONFIG_POWER_AVS_OMAP)		+= smartreflex.o
> diff --git a/drivers/soc/ti/k3-socinfo.c b/drivers/soc/ti/k3-socinfo.c
> index 5fae03004e350..9869dd6358d1f 100644
> --- a/drivers/soc/ti/k3-socinfo.c
> +++ b/drivers/soc/ti/k3-socinfo.c
> @@ -50,6 +50,7 @@
>   #define JTAG_ID_PARTNO_AM62PX		0xBB9D
>   #define JTAG_ID_PARTNO_J722S		0xBBA0
>   #define JTAG_ID_PARTNO_AM62LX		0xBBA7
> +#define JTAG_ID_PARTNO_TDA54		0xBBC1
>   
>   static const struct k3_soc_id {
>   	unsigned int id;
> @@ -66,6 +67,7 @@ static const struct k3_soc_id {
>   	{ JTAG_ID_PARTNO_AM62PX, "AM62PX" },
>   	{ JTAG_ID_PARTNO_J722S, "J722S" },
>   	{ JTAG_ID_PARTNO_AM62LX, "AM62LX" },
> +	{ JTAG_ID_PARTNO_TDA54, "TDA54" },
>   };
>   
>   static const char * const j721e_rev_string_map[] = {
> diff --git a/drivers/soc/ti/tda54-mcu-sysconf.c b/drivers/soc/ti/tda54-mcu-sysconf.c
> new file mode 100644
> index 0000000000000..8598080f6c48e
> --- /dev/null
> +++ b/drivers/soc/ti/tda54-mcu-sysconf.c
> @@ -0,0 +1,216 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * TDA54 SCM Configuration syscon driver
> + *
> + * Copyright (C) 2026 Texas Instruments Incorporated - https://www.ti.com/
> + */
> +#include <linux/bitfield.h>
> +#include <linux/bitops.h>
> +#include <linux/io.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/soc/ti/k3-socinfo.h>
> +#include <linux/types.h>
> +
> +/* Size of a single proxy window into the scm_conf register space */
> +#define TDA54_SCM_CONF_PROXY_STRIDE		0x4000
> +
> +#define TDA54_JTAG_ID_REG_OFFSET		0x14
> +
> +#define TDA54_SCM_CONF_LOCK_KICK0_UNLOCK_VAL	0x68EF3490
> +#define TDA54_SCM_CONF_LOCK_KICK1_UNLOCK_VAL	0xD172BC5A
> +
> +/*
> + * Claim registers start at 0x3100. Claim register i holds the claim bit
> + * for each of the 32 registers in the (i * TDA54_SCM_CONF_CLAIM_BLOCK_SIZE)
> + * .. (i * TDA54_SCM_CONF_CLAIM_BLOCK_SIZE + 0x7c) block, one bit per
> + * register, i.e. bit b of claim register i corresponds to the register at
> + * offset i * TDA54_SCM_CONF_CLAIM_BLOCK_SIZE + b * 4.
> + */
> +#define TDA54_SCM_CONF_CLAIM_REG_STRIDE		0x4
> +#define TDA54_SCM_CONF_CLAIM_REGS_PER_WORD	32
> +#define TDA54_SCM_CONF_CLAIM_BLOCK_SIZE		\
> +	(TDA54_SCM_CONF_CLAIM_REGS_PER_WORD * 0x4)
> +
> +/* Per-SoC register offset data (platform data) */
> +struct tda54_scm_conf_data {
> +	u32 lock_offset;
> +	u32 claim_offset;
> +	u32 claim_status_offset;
> +};
> +
> +static const struct tda54_scm_conf_data tda54_scm_conf_data = {
> +	.lock_offset		= 0x3008,
> +	.claim_offset		= 0x3100,
> +	.claim_status_offset	= 0x3300,
> +};
> +
> +struct tda54_scm_conf {
> +	void __iomem *base;
> +	u32 proxy;
> +	const struct tda54_scm_conf_data *pdata;
> +};
> +
> +/*
> + * Make @reg writable through this proxy.
> + *
> + * Proxy 0 is the default access proxy for all unclaimed registers. Its claim
> + * bits are tied low, so it cannot claim anything and needs no claim to write;
> + * it can write @reg unless another proxy has claimed it, which is reported by
> + * the claim status.
> + *
> + * Any other proxy has to claim @reg first. Registers claimed by a proxy can no
> + * longer be written through any other proxy's address, until that proxy
> + * releases the claim. The claim status is set once any proxy owns @reg, so
> + * read the claim register back to check that the claim is held by this proxy.
> + */
> +static int tda54_scm_conf_claim(struct tda54_scm_conf *scm, unsigned int reg)
> +{
> +	unsigned int block = reg / TDA54_SCM_CONF_CLAIM_BLOCK_SIZE;
> +	unsigned int bit = (reg % TDA54_SCM_CONF_CLAIM_BLOCK_SIZE) /
> +			   TDA54_SCM_CONF_CLAIM_REG_STRIDE;
> +	unsigned int claim_reg = scm->pdata->claim_offset +
> +				 block * TDA54_SCM_CONF_CLAIM_REG_STRIDE;
> +	unsigned int status_reg = scm->pdata->claim_status_offset +
> +				  block * TDA54_SCM_CONF_CLAIM_REG_STRIDE;
> +	u32 val;
> +
> +	if (!scm->proxy) {
> +		if (readl(scm->base + status_reg) & BIT(bit))
> +			return -EBUSY;
> +
> +		return 0;
> +	}
> +
> +	val = readl(scm->base + claim_reg);
> +	val |= BIT(bit);
> +	writel(val, scm->base + claim_reg);
> +
> +	if (!(readl(scm->base + claim_reg) & BIT(bit)))
> +		return -EBUSY;
> +
> +	return 0;
> +}
> +
> +static int tda54_scm_conf_reg_read(void *context, unsigned int reg,
> +				   unsigned int *val)
> +{
> +	struct tda54_scm_conf *scm = context;
> +
> +	*val = readl(scm->base + reg);
> +
> +	return 0;
> +}
> +
> +static int tda54_scm_conf_reg_write(void *context, unsigned int reg,
> +				    unsigned int val)
> +{
> +	struct tda54_scm_conf *scm = context;
> +	int ret;
> +
> +	ret = tda54_scm_conf_claim(scm, reg);
> +	if (ret)
> +		return ret;
> +
> +	writel(val, scm->base + reg);
> +
> +	return 0;
> +}
> +
> +static const struct regmap_config tda54_scm_conf_regmap_cfg = {
> +	.reg_bits = 32,
> +	.val_bits = 32,
> +	.reg_stride = 4,
> +	.reg_read = tda54_scm_conf_reg_read,
> +	.reg_write = tda54_scm_conf_reg_write,
> +};
> +
> +static int tda54_scm_conf_register_socinfo(struct device *dev,
> +					   struct regmap *regmap)
> +{
> +	u32 jtag_id;
> +	int ret;
> +
> +	ret = regmap_read(regmap, TDA54_JTAG_ID_REG_OFFSET, &jtag_id);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to read JTAG ID\n");
> +
> +	return k3_socinfo_register(dev, jtag_id);
> +}
> +
> +static int tda54_scm_conf_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct tda54_scm_conf *scm;
> +	struct regmap *regmap;
> +	void __iomem *base;
> +	int ret;
> +
> +	scm = devm_kzalloc(dev, sizeof(*scm), GFP_KERNEL);
> +	if (!scm)
> +		return -ENOMEM;
> +
> +	base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(base))
> +		return PTR_ERR(base);
> +
> +	if (of_property_read_u32(dev->of_node, "ti,proxy-id", &scm->proxy))
> +		return dev_err_probe(dev, -ENODATA, "missing ti,proxy-id property\n");
> +
> +	if (scm->proxy >= 8)
> +		return dev_err_probe(dev, -EINVAL,
> +				     "ti,proxy-id must be between 0 and 7\n");
> +
> +	scm->base = base + scm->proxy * TDA54_SCM_CONF_PROXY_STRIDE;
> +
> +	/* Get register offsets from driver data (matched by compatible) */
> +	scm->pdata = of_device_get_match_data(dev);
> +
> +	regmap = devm_regmap_init(dev, NULL, scm, &tda54_scm_conf_regmap_cfg);
> +	if (IS_ERR(regmap))
> +		return PTR_ERR(regmap);
> +
> +	writel(TDA54_SCM_CONF_LOCK_KICK0_UNLOCK_VAL, scm->base + scm->pdata->lock_offset);
> +	writel(TDA54_SCM_CONF_LOCK_KICK1_UNLOCK_VAL, scm->base + scm->pdata->lock_offset + 4);
> +
> +	/*
> +	 * There is no way to unregister a syscon regmap, so publish it only
> +	 * once nothing else in probe can fail.
> +	 */
> +	ret = of_syscon_register_regmap(dev->of_node, regmap);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to register syscon regmap\n");
> +
> +	/*
> +	 * SoC identification is informational, so a failure here must not fail
> +	 * the probe. It is registered last and released through devres.
> +	 */
> +	ret = tda54_scm_conf_register_socinfo(dev, regmap);
> +	if (ret)
> +		dev_warn(dev, "SoC info not registered: %d\n", ret);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id tda54_scm_conf_of_match[] = {
> +	{ .compatible = "ti,tda54-mcu-scm-conf", .data = &tda54_scm_conf_data },
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, tda54_scm_conf_of_match);
> +
> +static struct platform_driver tda54_scm_conf_driver = {
> +	.probe = tda54_scm_conf_probe,
> +	.driver = {
> +		.name = "k3-tda54-scm-conf",
> +		.of_match_table = tda54_scm_conf_of_match,
> +		.suppress_bind_attrs = true,
> +	},
> +};
> +
> +module_platform_driver(tda54_scm_conf_driver);
> +
> +MODULE_AUTHOR("Moteen Shah <m-shah@ti.com>");
> +MODULE_DESCRIPTION("TDA54 SCM Configuration syscon driver");
> +MODULE_LICENSE("GPL");

Hello all,

I was going by the reviews from Sashiko[0], I had similar concern before 
sharing this patch upstream.
It would be really great if I can have some suggestions on this.

1. Have it inbuilt
2. Remove the module_exit, make the module unremovable
3. Look towards a core syscon fixup?

Option 3 would be to add of_syscon_unregister_regmap(np) and subsequent 
consumer driver changes.

[0]https://sashiko.dev/#/patchset/20261019080736.944127-1-m-shah%40ti.com

Regards,
Moteen