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Date: Tue, 2 Nov 2021 11:26:59 +0100
From: Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
To: Sam Protsenko <semen.protsenko@...aro.org>,
Wim Van Sebroeck <wim@...ux-watchdog.org>,
Guenter Roeck <linux@...ck-us.net>,
Rob Herring <robh+dt@...nel.org>
Cc: linux-watchdog@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-samsung-soc@...r.kernel.org
Subject: Re: [PATCH v2 12/12] watchdog: s3c2410: Add Exynos850 support
On 31/10/2021 13:22, Sam Protsenko wrote:
> Exynos850 is a bit different from SoCs already supported in WDT driver:
> - AUTOMATIC_WDT_RESET_DISABLE register is removed, so its value is
> always 0; .disable_auto_reset callback is not set for that reason
> - MASK_WDT_RESET_REQUEST register is replaced with
> CLUSTERx_NONCPU_IN_EN register; instead of masking (disabling) WDT
> reset interrupt it's now enabled with the same value; .mask_reset
> callback is reused for that functionality though
> - To make WDT functional, WDT counter needs to be enabled in
> CLUSTERx_NONCPU_OUT register; it's done using .enable_counter
> callback
>
> Also Exynos850 has two CPU clusters, each has its own dedicated WDT
> instance. Different PMU registers and bits are used for each cluster. So
> driver data is now modified in probe, adding needed info depending on
> cluster index passed from device tree.
>
> Signed-off-by: Sam Protsenko <semen.protsenko@...aro.org>
> ---
> Changes in v2:
> - Used single compatible for Exynos850, populating missing driver data in
> probe
> - Added "index" property to specify CPU cluster index
>
> drivers/watchdog/s3c2410_wdt.c | 68 +++++++++++++++++++++++++++++++++-
> 1 file changed, 66 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
> index 8fdda2ede1c3..457b725c30ac 100644
> --- a/drivers/watchdog/s3c2410_wdt.c
> +++ b/drivers/watchdog/s3c2410_wdt.c
> @@ -56,6 +56,14 @@
> #define EXYNOS5_RST_STAT_REG_OFFSET 0x0404
> #define EXYNOS5_WDT_DISABLE_REG_OFFSET 0x0408
> #define EXYNOS5_WDT_MASK_RESET_REG_OFFSET 0x040c
> +#define EXYNOS850_CLUSTER0_NONCPU_OUT 0x1220
> +#define EXYNOS850_CLUSTER0_NONCPU_INT_EN 0x1244
> +#define EXYNOS850_CLUSTER1_NONCPU_OUT 0x1620
> +#define EXYNOS850_CLUSTER1_NONCPU_INT_EN 0x1644
> +
> +#define EXYNOS850_CLUSTER0_WDTRESET_BIT 24
> +#define EXYNOS850_CLUSTER1_WDTRESET_BIT 23
> +
> #define QUIRK_HAS_WTCLRINT_REG (1 << 0)
> #define QUIRK_HAS_PMU_MASK_RESET (1 << 1)
> #define QUIRK_HAS_PMU_RST_STAT (1 << 2)
> @@ -171,6 +179,21 @@ static const struct s3c2410_wdt_variant drv_data_exynos7 = {
> QUIRK_HAS_PMU_RST_STAT | QUIRK_HAS_PMU_AUTO_DISABLE,
> };
>
> +static const struct s3c2410_wdt_variant drv_data_exynos850 = {
> + /*
> + * Next fields will be set in probe(), based on cluster index:
> + * - .mask_reset_reg
> + * - .rst_stat_bit
> + * - .cnt_en_reg
> + */
> + .mask_reset_inv = true,
> + .mask_bit = 2,
> + .rst_stat_reg = EXYNOS5_RST_STAT_REG_OFFSET,
> + .cnt_en_bit = 7,
> + .quirks = QUIRK_HAS_WTCLRINT_REG | QUIRK_HAS_PMU_MASK_RESET | \
> + QUIRK_HAS_PMU_RST_STAT | QUIRK_HAS_PMU_CNT_EN,
> +};
> +
> static const struct of_device_id s3c2410_wdt_match[] = {
> { .compatible = "samsung,s3c2410-wdt",
> .data = &drv_data_s3c2410 },
> @@ -182,6 +205,8 @@ static const struct of_device_id s3c2410_wdt_match[] = {
> .data = &drv_data_exynos5420 },
> { .compatible = "samsung,exynos7-wdt",
> .data = &drv_data_exynos7 },
> + { .compatible = "samsung,exynos850-wdt",
> + .data = &drv_data_exynos850 },
> {},
> };
> MODULE_DEVICE_TABLE(of, s3c2410_wdt_match);
> @@ -548,15 +573,51 @@ static inline const struct s3c2410_wdt_variant *
> s3c2410_get_wdt_drv_data(struct platform_device *pdev)
> {
> const struct s3c2410_wdt_variant *variant;
> + struct s3c2410_wdt_variant *data;
> + struct device *dev = &pdev->dev;
>
> - variant = of_device_get_match_data(&pdev->dev);
> + variant = of_device_get_match_data(dev);
> if (!variant) {
> /* Device matched by platform_device_id */
> variant = (struct s3c2410_wdt_variant *)
> platform_get_device_id(pdev)->driver_data;
> }
>
> - return variant;
> + /* Have to copy driver data over to keep its const qualifier intact */
> + data = devm_kmemdup(dev, variant, sizeof(*variant), GFP_KERNEL);
> + if (!data)
> + return NULL;
> +
> + /* Populate missing fields for Exynos850 w.r.t. cluster index */
> + if (variant == &drv_data_exynos850) {
> + u32 index;
> + int err;
Another approach is to:
1. Define two variants for Exynos850 (s3c2410_wdt_variants), kind of
like before,
2. if (variant == &drv_data_exynos850)
a. Read the index
b. If index is 0, return first variant,
c. If index is 1, return the second variant,
d. Else - NULL.
This way you won't need to copy the memory on the fly, just use
different const data. Benefits: less memory allocations, entire drvdata
set in one place (so nicely visible), drvdata populated safely via const.
> +
> + err = of_property_read_u32(dev->of_node, "samsung,index",
> + &index);
> + if (err) {
> + dev_err(dev, "failed to get cluster index\n");
> + return NULL;
> + }
> +
> + switch (index) {
> + case 0:
> + data->mask_reset_reg = EXYNOS850_CLUSTER0_NONCPU_INT_EN;
> + data->rst_stat_bit = EXYNOS850_CLUSTER0_WDTRESET_BIT;
> + data->cnt_en_reg = EXYNOS850_CLUSTER0_NONCPU_OUT;
> + break;
> + case 1:
> + data->mask_reset_reg = EXYNOS850_CLUSTER1_NONCPU_INT_EN;
> + data->rst_stat_bit = EXYNOS850_CLUSTER1_WDTRESET_BIT;
> + data->cnt_en_reg = EXYNOS850_CLUSTER1_NONCPU_OUT;
> + break;
> + default:
> + dev_err(dev, "wrong cluster index: %u\n", index);
> + return NULL;
> + }
> + }
> +
> + return data;
> }
>
> static int s3c2410wdt_probe(struct platform_device *pdev)
> @@ -576,6 +637,9 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
> wdt->wdt_device = s3c2410_wdd;
>
> wdt->drv_data = s3c2410_get_wdt_drv_data(pdev);
> + if (!wdt->drv_data)
> + return -EINVAL;
> +
> if (wdt->drv_data->quirks & QUIRKS_HAVE_PMUREG) {
> wdt->pmureg = syscon_regmap_lookup_by_phandle(dev->of_node,
> "samsung,syscon-phandle");
>
Best regards,
Krzysztof
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