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Date: Tue, 23 Jul 2019 16:10:05 +0200
From: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: Sylwester Nawrocki <s.nawrocki@...sung.com>, robh+dt@...nel.org,
vireshk@...nel.org, devicetree@...r.kernel.org, kgene@...nel.org,
pankaj.dubey@...sung.com,
"linux-samsung-soc@...r.kernel.org"
<linux-samsung-soc@...r.kernel.org>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-pm@...r.kernel.org,
Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [PATCH v2 1/9] soc: samsung: Add exynos chipid driver support
Hi Krzysztof,
On 7/23/19 2:57 PM, Krzysztof Kozlowski wrote:
> On Thu, 18 Jul 2019 at 16:31, Sylwester Nawrocki <s.nawrocki@...sung.com> wrote:
>>
>> From: Pankaj Dubey <pankaj.dubey@...sung.com>
>>
>> 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.
>>
>> Changes by Bartlomiej:
>> - fixed return values on errors
>> - removed bogus kfree_const()
>> - added missing Exynos4210 EVT0 id
>> - converted code to use EXYNOS_MASK define
>> - fixed np use after of_node_put()
>> - fixed too early use of dev_info()
>> - made driver fail for unknown SoC-s
>> - added SPDX tag
>> - updated Copyrights
>>
>> Signed-off-by: Pankaj Dubey <pankaj.dubey@...sung.com>
>> [m.szyprowski: for suggestion and code snippet of product_id_to_soc_id]
>> Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
>> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
>> [s.nawrocki: updated copyright date]
>> Signed-off-by: Sylwester Nawrocki <s.nawrocki@...sung.com>
>> ---
>> drivers/soc/samsung/Kconfig | 5 ++
>> drivers/soc/samsung/Makefile | 2 +
>> drivers/soc/samsung/exynos-chipid.c | 111 ++++++++++++++++++++++++++++
>> 3 files changed, 118 insertions(+)
>> create mode 100644 drivers/soc/samsung/exynos-chipid.c
>>
>> diff --git a/drivers/soc/samsung/Kconfig b/drivers/soc/samsung/Kconfig
>> index 2186285fda92..2905f5262197 100644
>> --- a/drivers/soc/samsung/Kconfig
>> +++ b/drivers/soc/samsung/Kconfig
>> @@ -7,6 +7,11 @@ menuconfig SOC_SAMSUNG
>>
>> if SOC_SAMSUNG
>>
>> +config EXYNOS_CHIPID
>> + bool "Exynos Chipid controller driver" if COMPILE_TEST
>> + depends on ARCH_EXYNOS || COMPILE_TEST
>> + select SOC_BUS
>> +
>> config EXYNOS_PMU
>> bool "Exynos PMU controller driver" if COMPILE_TEST
>> depends on ARCH_EXYNOS || ((ARM || ARM64) && COMPILE_TEST)
>> diff --git a/drivers/soc/samsung/Makefile b/drivers/soc/samsung/Makefile
>> index 29f294baac6e..3b6a8797416c 100644
>> --- a/drivers/soc/samsung/Makefile
>> +++ b/drivers/soc/samsung/Makefile
>> @@ -1,4 +1,6 @@
>> # SPDX-License-Identifier: GPL-2.0
>> +
>> +obj-$(CONFIG_EXYNOS_CHIPID) += exynos-chipid.o
>> obj-$(CONFIG_EXYNOS_PMU) += exynos-pmu.o
>>
>> obj-$(CONFIG_EXYNOS_PMU_ARM_DRIVERS) += exynos3250-pmu.o exynos4-pmu.o \
>> diff --git a/drivers/soc/samsung/exynos-chipid.c b/drivers/soc/samsung/exynos-chipid.c
>> new file mode 100644
>> index 000000000000..78b123ee60c0
>> --- /dev/null
>> +++ b/drivers/soc/samsung/exynos-chipid.c
>> @@ -0,0 +1,111 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (c) 2019 Samsung Electronics Co., Ltd.
>> + * http://www.samsung.com/
>> + *
>> + * EXYNOS - CHIP ID support
>> + * Author: Pankaj Dubey <pankaj.dubey@...sung.com>
>> + * Author: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
>> + */
>> +
>> +#include <linux/io.h>
>> +#include <linux/of.h>
>> +#include <linux/of_address.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/platform_device.h>
>
> Any changes here from my previous comments?
>
> I have also one more new thought later.
>
>> +#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)
>> +#define EXYNOS_MASK 0xFFFFF000
>> +
>> +static const struct exynos_soc_id {
>> + const char *name;
>> + unsigned int id;
>> +} soc_ids[] = {
>> + { "EXYNOS3250", 0xE3472000 },
>> + { "EXYNOS4210", 0x43200000 }, /* EVT0 revision */
>> + { "EXYNOS4210", 0x43210000 },
>> + { "EXYNOS4212", 0x43220000 },
>> + { "EXYNOS4412", 0xE4412000 },
>> + { "EXYNOS5250", 0x43520000 },
>> + { "EXYNOS5260", 0xE5260000 },
>> + { "EXYNOS5410", 0xE5410000 },
>> + { "EXYNOS5420", 0xE5420000 },
>> + { "EXYNOS5440", 0xE5440000 },
>> + { "EXYNOS5800", 0xE5422000 },
>> + { "EXYNOS7420", 0xE7420000 },
>> + { "EXYNOS5433", 0xE5433000 },
>> +};
>> +
>> +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 & EXYNOS_MASK) == soc_ids[i].id)
>> + return soc_ids[i].name;
>> + return NULL;
>> +}
>> +
>> +int __init exynos_chipid_early_init(void)
>> +{
>> + struct soc_device_attribute *soc_dev_attr;
>> + void __iomem *exynos_chipid_base;
>> + struct soc_device *soc_dev;
>> + struct device_node *root;
>> + struct device_node *np;
>> + u32 product_id;
>> + u32 revision;
>> +
>> + /* look up for chipid node */
>> + np = of_find_compatible_node(NULL, NULL, "samsung,exynos4210-chipid");
>> + if (!np)
>> + return -ENODEV;
>> +
>> + exynos_chipid_base = of_iomap(np, 0);
>> + of_node_put(np);
>> +
>> + if (!exynos_chipid_base) {
>> + pr_err("Failed to map SoC chipid\n");
>> + return -ENXIO;
>> + }
>> +
>> + 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 -ENOMEM;
>> +
>> + 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);
>> + if (!soc_dev_attr->soc_id) {
>> + pr_err("Unknown SoC\n");
>
> In case of running old kernel on unknown SoC (new revision of existing
> one or older design not longer supported like 4415), the device will
> not bind. This was added by Bartlomiej. Why? I imagine that soc driver
> could be still matched and just report "Unknown". I am not sure if
> this changes anything, though.
I was thinking that we shouldn't be pretending that we know how to
handle unsupported SoCs, i.e. that we know how to correctly read its
product_id and revision.
Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics
> Best regards,
> Krzysztof
>
>
>> + return -ENODEV;
>> + }
>> +
>> + /* please note that the actual registration will be deferred */
>> + soc_dev = soc_device_register(soc_dev_attr);
>> + if (IS_ERR(soc_dev)) {
>> + kfree(soc_dev_attr->revision);
>> + kfree(soc_dev_attr);
>> + return PTR_ERR(soc_dev);
>> + }
>> +
>> + /* it is too early to use dev_info() here (soc_dev is NULL) */
>> + pr_info("soc soc0: Exynos: CPU[%s] PRO_ID[0x%x] REV[0x%x] Detected\n",
>> + soc_dev_attr->soc_id, product_id, revision);
>> +
>> + return 0;
>> +}
>> +early_initcall(exynos_chipid_early_init);
>> --
>> 2.17.1
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