Re: [PATCH v2] nvmem: add QTI SDAM driver

[sthella@codeaurora.org]

On 2019-12-23 16:22, Shyam Kumar Thella wrote:
> From: Anirudh Ghayal <aghayal@codeaurora.org>
> 
> QTI SDAM driver allows PMIC peripherals to access the shared memory
> that is available on QTI PMICs.
> 
> Use subsys_initcall as PMIC SDAM NV memory is accessed by multiple PMIC
> drivers (charger, fuel guage) to store/restore data across reboots
> required during their initialization.
> 
> Signed-off-by: Shyam Kumar Thella <sthella@codeaurora.org>
> ---
>  drivers/nvmem/Kconfig          |   8 ++
>  drivers/nvmem/Makefile         |   1 +
>  drivers/nvmem/qcom-spmi-sdam.c | 189 
> +++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 198 insertions(+)
>  create mode 100644 drivers/nvmem/qcom-spmi-sdam.c
> 
> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
> index 73567e9..35efab1 100644
> --- a/drivers/nvmem/Kconfig
> +++ b/drivers/nvmem/Kconfig
> @@ -109,6 +109,14 @@ config QCOM_QFPROM
>  	  This driver can also be built as a module. If so, the module
>  	  will be called nvmem_qfprom.
> 
> +config NVMEM_SPMI_SDAM
> +	tristate "SPMI SDAM Support"
> +	depends on SPMI
> +	help
> +	  This driver supports the Shared Direct Access Memory Module on
> +	  Qualcomm Technologies, Inc. PMICs. It provides the clients
> +	  an interface to read/write to the SDAM module's shared memory.
> +
>  config ROCKCHIP_EFUSE
>  	tristate "Rockchip eFuse Support"
>  	depends on ARCH_ROCKCHIP || COMPILE_TEST
> diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
> index 9e66782..877a0b0 100644
> --- a/drivers/nvmem/Makefile
> +++ b/drivers/nvmem/Makefile
> @@ -28,6 +28,7 @@ obj-$(CONFIG_MTK_EFUSE)		+= nvmem_mtk-efuse.o
>  nvmem_mtk-efuse-y		:= mtk-efuse.o
>  obj-$(CONFIG_QCOM_QFPROM)	+= nvmem_qfprom.o
>  nvmem_qfprom-y			:= qfprom.o
> +obj-$(CONFIG_NVMEM_SPMI_SDAM)	+= qcom-spmi-sdam.o
>  obj-$(CONFIG_ROCKCHIP_EFUSE)	+= nvmem_rockchip_efuse.o
>  nvmem_rockchip_efuse-y		:= rockchip-efuse.o
>  obj-$(CONFIG_ROCKCHIP_OTP)	+= nvmem-rockchip-otp.o
> diff --git a/drivers/nvmem/qcom-spmi-sdam.c 
> b/drivers/nvmem/qcom-spmi-sdam.c
> new file mode 100644
> index 0000000..e11228e
> --- /dev/null
> +++ b/drivers/nvmem/qcom-spmi-sdam.c
> @@ -0,0 +1,189 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2017 The Linux Foundation. All rights reserved.
> + */
> +
> +#include <linux/device.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
> +#include <linux/nvmem-provider.h>
> +#include <linux/regmap.h>
> +
> +#define SDAM_MEM_START			0x40
> +#define REGISTER_MAP_ID			0x40
> +#define REGISTER_MAP_VERSION		0x41
> +#define SDAM_SIZE			0x44
> +#define SDAM_PBS_TRIG_SET		0xE5
> +#define SDAM_PBS_TRIG_CLR		0xE6
> +
> +struct sdam_chip {
> +	struct platform_device		*pdev;
> +	struct regmap			*regmap;
> +	struct nvmem_config		sdam_config;
> +	unsigned int			base;
> +	unsigned int			size;
> +};
> +
> +/* read only register offsets */
> +static const u8 sdam_ro_map[] = {
> +	REGISTER_MAP_ID,
> +	REGISTER_MAP_VERSION,
> +	SDAM_SIZE
> +};
> +
> +static bool sdam_is_valid(struct sdam_chip *sdam, unsigned int offset,
> +				size_t len)
> +{
> +	unsigned int sdam_mem_end = SDAM_MEM_START + sdam->size - 1;
> +
> +	if (!len)
> +		return false;
> +
> +	if (offset >= SDAM_MEM_START && offset <= sdam_mem_end
> +				&& (offset + len - 1) <= sdam_mem_end)
> +		return true;
> +	else if ((offset == SDAM_PBS_TRIG_SET || offset == SDAM_PBS_TRIG_CLR)
> +				&& (len == 1))
> +		return true;
> +
> +	return false;
> +}
> +
> +static bool sdam_is_ro(unsigned int offset, size_t len)
> +{
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(sdam_ro_map); i++)
> +		if (offset <= sdam_ro_map[i] && (offset + len) > sdam_ro_map[i])
> +			return true;
> +
> +	return false;
> +}
> +
> +static int sdam_read(void *priv, unsigned int offset, void *val,
> +				size_t bytes)
> +{
> +	struct sdam_chip *sdam = priv;
> +	struct device *dev = &sdam->pdev->dev;
> +	int rc;
> +
> +	if (!sdam_is_valid(sdam, offset, bytes)) {
> +		dev_err(dev, "Invalid SDAM offset %#x len=%zd\n", offset, bytes);
> +		return -EINVAL;
> +	}
> +
> +	rc = regmap_bulk_read(sdam->regmap, sdam->base + offset, val, bytes);
> +	if (rc < 0)
> +		dev_err(dev, "Failed to read SDAM offset %#x len=%zd, rc=%d\n",
> +						offset, bytes, rc);
> +
> +	return rc;
> +}
> +
> +static int sdam_write(void *priv, unsigned int offset, void *val,
> +				size_t bytes)
> +{
> +	struct sdam_chip *sdam = priv;
> +	struct device *dev = &sdam->pdev->dev;
> +	int rc;
> +
> +	if (!sdam_is_valid(sdam, offset, bytes)) {
> +		dev_err(dev, "Invalid SDAM offset %#x len=%zd\n", offset, bytes);
> +		return -EINVAL;
> +	}
> +
> +	if (sdam_is_ro(offset, bytes)) {
> +		dev_err(dev, "Invalid write offset %#x len=%zd\n", offset, bytes);
> +		return -EINVAL;
> +	}
> +
> +	rc = regmap_bulk_write(sdam->regmap, sdam->base + offset, val, 
> bytes);
> +	if (rc < 0)
> +		dev_err(dev, "Failed to write SDAM offset %#x len=%zd, rc=%d\n",
> +						offset, bytes, rc);
> +
> +	return rc;
> +}
> +
> +static int sdam_probe(struct platform_device *pdev)
> +{
> +	struct sdam_chip *sdam;
> +	struct nvmem_device *nvmem;
> +	unsigned int val;
> +	int rc;
> +
> +	sdam = devm_kzalloc(&pdev->dev, sizeof(*sdam), GFP_KERNEL);
> +	if (!sdam)
> +		return -ENOMEM;
> +
> +	sdam->regmap = dev_get_regmap(pdev->dev.parent, NULL);
> +	if (!sdam->regmap) {
> +		dev_err(&pdev->dev, "Failed to get regmap handle\n");
> +		return -ENXIO;
> +	}
> +
> +	rc = of_property_read_u32(pdev->dev.of_node, "reg", &sdam->base);
> +	if (rc < 0) {
> +		dev_err(&pdev->dev, "Failed to get SDAM base, rc=%d\n", rc);
> +		return -EINVAL;
> +	}
> +
> +	rc = regmap_read(sdam->regmap, sdam->base + SDAM_SIZE, &val);
> +	if (rc < 0) {
> +		dev_err(&pdev->dev, "Failed to read SDAM_SIZE rc=%d\n", rc);
> +		return -EINVAL;
> +	}
> +	sdam->size = val * 32;
> +
> +	sdam->sdam_config.dev = &pdev->dev;
> +	sdam->sdam_config.name = "spmi_sdam";
> +	sdam->sdam_config.id = pdev->id;
> +	sdam->sdam_config.owner = THIS_MODULE,
> +	sdam->sdam_config.stride = 1;
> +	sdam->sdam_config.word_size = 1;
> +	sdam->sdam_config.reg_read = sdam_read;
> +	sdam->sdam_config.reg_write = sdam_write;
> +	sdam->sdam_config.priv = sdam;
> +
> +	nvmem = devm_nvmem_register(&pdev->dev, &sdam->sdam_config);
> +	if (IS_ERR(nvmem)) {
> +		dev_err(&pdev->dev,
> +			"Failed to register SDAM nvmem device rc=%ld\n",
> +			PTR_ERR(nvmem));
> +		return -ENXIO;
> +	}
> +	dev_dbg(&pdev->dev,
> +		"SDAM base=%#x size=%u registered successfully\n",
> +		sdam->base, sdam->size);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id sdam_match_table[] = {
> +	{ .compatible = "qcom,spmi-sdam" },
> +	{},
> +};
> +
> +static struct platform_driver sdam_driver = {
> +	.driver = {
> +		.name = "qcom,spmi-sdam",
> +		.of_match_table = sdam_match_table,
> +	},
> +	.probe		= sdam_probe,
> +};
> +
> +static int __init sdam_init(void)
> +{
> +	return platform_driver_register(&sdam_driver);
> +}
> +subsys_initcall(sdam_init);
> +
> +static void __exit sdam_exit(void)
> +{
> +	return platform_driver_unregister(&sdam_driver);
> +}
> +module_exit(sdam_exit);
> +
> +MODULE_DESCRIPTION("QCOM SPMI SDAM driver");
> +MODULE_LICENSE("GPL v2");

DT bindings for this driver is available at 
https://lkml.org/lkml/2020/1/14/51

Regards,
Shyam