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Message-ID: <20201105090628.GA75895@kozik-lap>
Date: Thu, 5 Nov 2020 10:06:28 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Alice Guo <alice.guo@....com>
Cc: robh+dt@...nel.org, shawnguo@...nel.org, s.hauer@...gutronix.de,
linux-imx@....com, peng.fan@....com, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 4/4] soc: imx8m: change to use platform driver
On Thu, Nov 05, 2020 at 03:26:29PM +0800, Alice Guo wrote:
> Directly reading ocotp register depends on that bootloader enables ocotp
> clk, which is not always effective, so change to use nvmem API. Using
> nvmem API requires to support driver defer probe and thus change
> soc-imx8m.c to use platform driver.
>
> The other reason is that directly reading ocotp register causes kexec
> kernel hang because the 1st kernel running will disable unused clks
> after kernel boots up, and then ocotp clk will be disabled even if
> bootloader enables it. When kexec kernel, ocotp clk needs to be enabled
> before reading ocotp registers, and nvmem API with platform driver
> supported can accomplish this.
>
> Signed-off-by: Alice Guo <alice.guo@....com>
> ---
> drivers/soc/imx/soc-imx8m.c | 75 +++++++++++++++++++++----------------
> 1 file changed, 42 insertions(+), 33 deletions(-)
>
> diff --git a/drivers/soc/imx/soc-imx8m.c b/drivers/soc/imx/soc-imx8m.c
> index cc57a384d74d..83f3297509be 100644
> --- a/drivers/soc/imx/soc-imx8m.c
> +++ b/drivers/soc/imx/soc-imx8m.c
> @@ -5,6 +5,8 @@
>
> #include <linux/init.h>
> #include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/nvmem-consumer.h>
> #include <linux/of_address.h>
> #include <linux/slab.h>
> #include <linux/sys_soc.h>
> @@ -29,7 +31,7 @@
>
> struct imx8_soc_data {
> char *name;
> - u32 (*soc_revision)(void);
> + u32 (*soc_revision)(struct device *dev);
> };
>
> static u64 soc_uid;
> @@ -50,12 +52,15 @@ static u32 imx8mq_soc_revision_from_atf(void)
> static inline u32 imx8mq_soc_revision_from_atf(void) { return 0; };
> #endif
>
> -static u32 __init imx8mq_soc_revision(void)
> +static u32 __init imx8mm_soc_uid(struct device *dev);
> +
> +static u32 __init imx8mq_soc_revision(struct device *dev)
> {
> struct device_node *np;
> void __iomem *ocotp_base;
> u32 magic;
> u32 rev;
> + int ret = 0;
>
> np = of_find_compatible_node(NULL, NULL, "fsl,imx8mq-ocotp");
> if (!np)
> @@ -75,9 +80,9 @@ static u32 __init imx8mq_soc_revision(void)
> rev = REV_B1;
> }
>
> - soc_uid = readl_relaxed(ocotp_base + OCOTP_UID_HIGH);
> - soc_uid <<= 32;
> - soc_uid |= readl_relaxed(ocotp_base + OCOTP_UID_LOW);
> + ret = imx8mm_soc_uid(dev);
> + if (ret)
> + return ret;
>
> iounmap(ocotp_base);
> of_node_put(np);
> @@ -85,33 +90,20 @@ static u32 __init imx8mq_soc_revision(void)
> return rev;
> }
>
> -static void __init imx8mm_soc_uid(void)
> +static u32 __init imx8mm_soc_uid(struct device *dev)
> {
> - void __iomem *ocotp_base;
> - struct device_node *np;
> - u32 offset = of_machine_is_compatible("fsl,imx8mp") ?
> - IMX8MP_OCOTP_UID_OFFSET : 0;
> -
> - np = of_find_compatible_node(NULL, NULL, "fsl,imx8mm-ocotp");
> - if (!np)
> - return;
> -
> - ocotp_base = of_iomap(np, 0);
> - WARN_ON(!ocotp_base);
> -
> - soc_uid = readl_relaxed(ocotp_base + OCOTP_UID_HIGH + offset);
> - soc_uid <<= 32;
> - soc_uid |= readl_relaxed(ocotp_base + OCOTP_UID_LOW + offset);
> + int ret = 0;
>
> - iounmap(ocotp_base);
> - of_node_put(np);
> + ret = nvmem_cell_read_u64(dev, "soc_unique_id", &soc_uid);
> + return ret;
> }
>
> -static u32 __init imx8mm_soc_revision(void)
> +static u32 __init imx8mm_soc_revision(struct device *dev)
> {
> struct device_node *np;
> void __iomem *anatop_base;
> u32 rev;
> + int ret;
>
> np = of_find_compatible_node(NULL, NULL, "fsl,imx8mm-anatop");
> if (!np)
> @@ -125,7 +117,9 @@ static u32 __init imx8mm_soc_revision(void)
> iounmap(anatop_base);
> of_node_put(np);
>
> - imx8mm_soc_uid();
> + ret = imx8mm_soc_uid(dev);
> + if (ret)
> + return ret;
I think this breaks old existing DTBs. If applied on separate branch
than DTS patches, it will cause bisect regressions. Regardless of it,
all out-of-tree (customer DTBs) will start failing here as well.
Best regards,
Krzysztof
>
> return rev;
> }
> @@ -151,19 +145,20 @@ static const struct imx8_soc_data imx8mp_soc_data = {
> };
>
> static __maybe_unused const struct of_device_id imx8_soc_match[] = {
> - { .compatible = "fsl,imx8mq", .data = &imx8mq_soc_data, },
> - { .compatible = "fsl,imx8mm", .data = &imx8mm_soc_data, },
> - { .compatible = "fsl,imx8mn", .data = &imx8mn_soc_data, },
> - { .compatible = "fsl,imx8mp", .data = &imx8mp_soc_data, },
> + { .compatible = "fsl,imx8mq-soc", .data = &imx8mq_soc_data, },
> + { .compatible = "fsl,imx8mm-soc", .data = &imx8mm_soc_data, },
> + { .compatible = "fsl,imx8mn-soc", .data = &imx8mn_soc_data, },
> + { .compatible = "fsl,imx8mp-soc", .data = &imx8mp_soc_data, },
> { }
> };
> +MODULE_DEVICE_TABLE(of, imx8_soc_match);
>
> #define imx8_revision(soc_rev) \
> soc_rev ? \
> kasprintf(GFP_KERNEL, "%d.%d", (soc_rev >> 4) & 0xf, soc_rev & 0xf) : \
> "unknown"
>
> -static int __init imx8_soc_init(void)
> +static int imx8_soc_init_probe(struct platform_device *pdev)
> {
> struct soc_device_attribute *soc_dev_attr;
> struct soc_device *soc_dev;
> @@ -182,7 +177,7 @@ static int __init imx8_soc_init(void)
> if (ret)
> goto free_soc;
>
> - id = of_match_node(imx8_soc_match, of_root);
> + id = of_match_node(imx8_soc_match, pdev->dev.of_node);
> if (!id) {
> ret = -ENODEV;
> goto free_soc;
> @@ -192,7 +187,11 @@ static int __init imx8_soc_init(void)
> if (data) {
> soc_dev_attr->soc_id = data->name;
> if (data->soc_revision)
> - soc_rev = data->soc_revision();
> + soc_rev = data->soc_revision(&pdev->dev);
> +
> + ret = soc_rev;
> + if (ret < 0)
> + goto free_soc;
> }
>
> soc_dev_attr->revision = imx8_revision(soc_rev);
> @@ -230,4 +229,14 @@ static int __init imx8_soc_init(void)
> kfree(soc_dev_attr);
> return ret;
> }
> -device_initcall(imx8_soc_init);
> +
> +static struct platform_driver imx8_soc_init_driver = {
> + .probe = imx8_soc_init_probe,
> + .driver = {
> + .name = "imx8_soc_init",
> + .of_match_table = of_match_ptr(imx8_soc_match),
> + },
> +};
> +
> +module_platform_driver(imx8_soc_init_driver);
> +MODULE_LICENSE("GPL v2");
> --
> 2.17.1
>
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