Re: [PATCH v8 1/8] soc: samsung: add exynos chipid driver support

[Andrzej Hajda <a.hajda@samsung.com>]

On 10.12.2016 14:08, Pankaj Dubey wrote:
> Exynos SoCs have Chipid, for identification of product IDs and SoC revisions.
> This patch intends to provide initialization code for all these functionalities,
> at the same time it provides some sysfs entries for accessing these information
> to user-space.
>
> This driver uses existing binding for exynos-chipid.
>
> CC: Grant Likely <grant.likely@linaro.org>
> CC: Rob Herring <robh+dt@kernel.org>
> CC: Linus Walleij <linus.walleij@linaro.org>
> Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com>
> [m.szyprowski: for suggestion and code snippet of product_id_to_soc_id]
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> ---
>  drivers/soc/samsung/Kconfig         |   5 ++
>  drivers/soc/samsung/Makefile        |   1 +
>  drivers/soc/samsung/exynos-chipid.c | 116 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 122 insertions(+)
>  create mode 100644 drivers/soc/samsung/exynos-chipid.c
>
> diff --git a/drivers/soc/samsung/Kconfig b/drivers/soc/samsung/Kconfig
> index 2455339..f9ab858 100644
> --- a/drivers/soc/samsung/Kconfig
> +++ b/drivers/soc/samsung/Kconfig
> @@ -14,4 +14,9 @@ config EXYNOS_PM_DOMAINS
>  	bool "Exynos PM domains" if COMPILE_TEST
>  	depends on PM_GENERIC_DOMAINS || COMPILE_TEST
>  
> +config EXYNOS_CHIPID
> +	bool "Exynos Chipid controller driver" if COMPILE_TEST
> +	depends on (ARM && ARCH_EXYNOS) || ((ARM || ARM64) && COMPILE_TEST)
> +	select SOC_BUS
> +
>  endif
> diff --git a/drivers/soc/samsung/Makefile b/drivers/soc/samsung/Makefile
> index 3619f2e..2a8a85e 100644
> --- a/drivers/soc/samsung/Makefile
> +++ b/drivers/soc/samsung/Makefile
> @@ -1,3 +1,4 @@
>  obj-$(CONFIG_EXYNOS_PMU)	+= exynos-pmu.o exynos3250-pmu.o exynos4-pmu.o \
>  					exynos5250-pmu.o exynos5420-pmu.o
>  obj-$(CONFIG_EXYNOS_PM_DOMAINS) += pm_domains.o
> +obj-$(CONFIG_EXYNOS_CHIPID)	+= exynos-chipid.o
> diff --git a/drivers/soc/samsung/exynos-chipid.c b/drivers/soc/samsung/exynos-chipid.c
> new file mode 100644
> index 0000000..cf0128b
> --- /dev/null
> +++ b/drivers/soc/samsung/exynos-chipid.c
> @@ -0,0 +1,116 @@
> +/*
> + * Copyright (c) 2016 Samsung Electronics Co., Ltd.
> + *	      http://www.samsung.com/
> + *
> + * EXYNOS - CHIP ID support
> + * Author: Pankaj Dubey <pankaj.dubey@samsung.com>
> + *
> + * 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.
> + */
> +
> +#include <linux/io.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/sys_soc.h>
> +
> +#define EXYNOS_SUBREV_MASK	(0xF << 4)
> +#define EXYNOS_MAINREV_MASK	(0xF << 0)
> +#define EXYNOS_REV_MASK		(EXYNOS_SUBREV_MASK | EXYNOS_MAINREV_MASK)
> +
> +static const struct exynos_soc_id {
> +	const char *name;
> +	unsigned int id;
> +	unsigned int mask;
> +} soc_ids[] = {
> +	{ "EXYNOS3250", 0xE3472000, 0xFFFFF000 },
> +	{ "EXYNOS4210", 0x43200000, 0xFFFE0000 },
> +	{ "EXYNOS4212", 0x43220000, 0xFFFE0000 },
> +	{ "EXYNOS4412", 0xE4412000, 0xFFFE0000 },
> +	{ "EXYNOS5250", 0x43520000, 0xFFFFF000 },
> +	{ "EXYNOS5260", 0xE5260000, 0xFFFFF000 },
> +	{ "EXYNOS5410", 0xE5410000, 0xFFFFF000 },
> +	{ "EXYNOS5420", 0xE5420000, 0xFFFFF000 },
> +	{ "EXYNOS5440", 0xE5440000, 0xFFFFF000 },
> +	{ "EXYNOS5800", 0xE5422000, 0xFFFFF000 },
> +	{ "EXYNOS7420", 0xE7420000, 0xFFFFF000 },
> +	{ "EXYNOS5433", 0xE5433000, 0xFFFFF000 },

I wonder why there are different masks in case of Exynos42*?
In specs I have access to mask is always 0xFFFFF000.


> +};
> +
> +static const char * __init product_id_to_soc_id(unsigned int product_id)
> +{
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(soc_ids); i++)
> +		if ((product_id & soc_ids[i].mask) == soc_ids[i].id)
> +			return soc_ids[i].name;
> +	return "UNKNOWN";
> +}
> +
> +static const struct of_device_id of_exynos_chipid_ids[] = {
> +	{
> +		.compatible	= "samsung,exynos4210-chipid",
> +	},
> +	{},
> +};
> +
> +/**
> + *  exynos_chipid_early_init: Early chipid initialization
> + */
> +int __init exynos_chipid_early_init(void)
> +{
> +	struct soc_device_attribute *soc_dev_attr;
> +	struct soc_device *soc_dev;
> +	struct device_node *root;
> +	struct device_node *np;
> +	void __iomem *exynos_chipid_base;
> +	const struct of_device_id *match;
> +	u32 product_id;
> +	u32 revision;
> +
> +	np = of_find_matching_node_and_match(NULL,
> +			of_exynos_chipid_ids, &match);
> +	if (!np)
> +		return -ENODEV;
> +
> +	exynos_chipid_base = of_iomap(np, 0);
> +
> +	if (!exynos_chipid_base)
> +		return PTR_ERR(exynos_chipid_base);
> +
> +	product_id  = readl_relaxed(exynos_chipid_base);
> +	revision = product_id & EXYNOS_REV_MASK;
> +	iounmap(exynos_chipid_base);
> +
> +	soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
> +	if (!soc_dev_attr)
> +		return -ENODEV;
> +
> +	soc_dev_attr->family = "Samsung Exynos";
> +
> +	root = of_find_node_by_path("/");
> +	of_property_read_string(root, "model", &soc_dev_attr->machine);
> +	of_node_put(root);
> +
> +	soc_dev_attr->revision = kasprintf(GFP_KERNEL, "%x", revision);
> +	soc_dev_attr->soc_id = product_id_to_soc_id(product_id);
> +
> +
> +	pr_info("Exynos: CPU[%s] CPU_REV[0x%x] Detected\n",
> +			product_id_to_soc_id(product_id), revision);

I wonder if it wouldn't be good to log numeric value of whole PRO_ID
register, this way we will have also useful log for chips not know to
soc_ids array.
It will show also some missing bits: masked bits, package_information
and reserved bit. Btw. package_information can be used to distinguish
S5PC210 and S5PV310.
And small optimization, you can reuse soc_dev_attr->soc_id instead of
calling the same function again.
And finally all log could be moved after soc_device_register, this way
you can use:
    struc device *dev = soc_device_to_device(soc_dev);
    dev_info(dev, ...);

Regards
Andrzej

> +
> +	soc_dev = soc_device_register(soc_dev_attr);
> +	if (IS_ERR(soc_dev)) {
> +		kfree(soc_dev_attr->revision);
> +		kfree_const(soc_dev_attr->soc_id);
> +		kfree(soc_dev_attr);
> +		return PTR_ERR(soc_dev);
> +	}
> +
> +	return 0;
> +}
> +early_initcall(exynos_chipid_early_init);