linux-kernel - Re: [PATCH v2] soc: imx: Add SoC device register for i.MX9

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Message-ID: <30bd4862-daa9-41bb-95dc-990ea462dc95@gmx.net>
Date: Tue, 29 Oct 2024 10:13:01 +0100
From: Stefan Wahren <wahrenst@....net>
To: alice.guo@....nxp.com, shawnguo@...nel.org, s.hauer@...gutronix.de,
 kernel@...gutronix.de, festevam@...il.com
Cc: imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, "alice.guo" <alice.guo@....com>
Subject: Re: [PATCH v2] soc: imx: Add SoC device register for i.MX9

Hi Alice,

Am 29.10.24 um 09:34 schrieb alice.guo@....nxp.com:
> From: "alice.guo" <alice.guo@....com>
>
> i.MX9 SoCs have SoC ID, SoC revision number and chip unique identifier
> which are provided by the corresponding ARM trusted firmware API. This
> patch intends to use SMC call to obtain these information and then
> register i.MX9 SoC as a device.
>
> Signed-off-by: alice.guo <alice.guo@....com>
> ---
>
> Changes for v2:
>   - refine error log print
>
>   drivers/soc/imx/Makefile   |   2 +-
>   drivers/soc/imx/soc-imx9.c | 103 +++++++++++++++++++++++++++++++++++++
>   2 files changed, 104 insertions(+), 1 deletion(-)
>   create mode 100644 drivers/soc/imx/soc-imx9.c
>
> diff --git a/drivers/soc/imx/Makefile b/drivers/soc/imx/Makefile
> index 3ad321ca608a..ca6a5fa1618f 100644
> --- a/drivers/soc/imx/Makefile
> +++ b/drivers/soc/imx/Makefile
> @@ -3,4 +3,4 @@ ifeq ($(CONFIG_ARM),y)
>   obj-$(CONFIG_ARCH_MXC) += soc-imx.o
>   endif
>   obj-$(CONFIG_SOC_IMX8M) += soc-imx8m.o
> -obj-$(CONFIG_SOC_IMX9) += imx93-src.o
> +obj-$(CONFIG_SOC_IMX9) += imx93-src.o soc-imx9.o
> diff --git a/drivers/soc/imx/soc-imx9.c b/drivers/soc/imx/soc-imx9.c
> new file mode 100644
> index 000000000000..0722e69110f9
> --- /dev/null
> +++ b/drivers/soc/imx/soc-imx9.c
> @@ -0,0 +1,103 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright 2024 NXP
> + */
> +
> +#include <linux/arm-smccc.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/slab.h>
> +#include <linux/sys_soc.h>
> +
> +#define IMX_SIP_GET_SOC_INFO	0xc2000006
> +#define SOC_ID(x)		(((x) & 0xFFFF) >> 8)
> +#define SOC_REV_MAJOR(x)	((((x) >> 28) & 0xF) - 0x9)
> +#define SOC_REV_MINOR(x)	(((x) >> 24) & 0xF)
> +
> +static int imx9_soc_device_register(void)
> +{
> +	struct soc_device_attribute *attr;
> +	struct arm_smccc_res res;
> +	struct soc_device *sdev;
> +	u32 soc_id, rev_major, rev_minor;
> +	u64 uid127_64, uid63_0;
> +	int err;
> +
> +	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
> +	if (!attr)
> +		return -ENOMEM;
> +
> +	err = of_property_read_string(of_root, "model", &attr->machine);
> +	if (err) {
> +		pr_err("%s: missing model property: %d\n", __func__, err);
> +		goto attr;
> +	}
> +
> +	attr->family = kasprintf(GFP_KERNEL, "Freescale i.MX");
> +
> +	/*
> +	 * Retrieve the soc id, rev & uid info:
> +	 * res.a1[31:16]: soc revision;
> +	 * res.a1[15:0]: soc id;
> +	 * res.a2: uid[127:64];
> +	 * res.a3: uid[63:0];
> +	 */
> +	arm_smccc_smc(IMX_SIP_GET_SOC_INFO, 0, 0, 0, 0, 0, 0, 0, &res);
> +	if (res.a0 != SMCCC_RET_SUCCESS) {
> +		pr_err("%s: SMC failed: %d\n", __func__, res.a0);
> +		err = res.a0;
The pr_err() looks good to me. But in this specific case, I would stick
with assigning -EINVAL to err, because the SMCCC_RET.. codes are
completely different from Linux. I wasn't clear about that in my last
comment.
> +		goto family;
> +	}
> +
> +	soc_id = SOC_ID(res.a1);
> +	rev_major = SOC_REV_MAJOR(res.a1);
> +	rev_minor = SOC_REV_MINOR(res.a1);
> +
> +	attr->soc_id = kasprintf(GFP_KERNEL, "i.MX%2x", soc_id);
> +	attr->revision = kasprintf(GFP_KERNEL, "%d.%d", rev_major, rev_minor);
> +
> +	uid127_64 = res.a2;
> +	uid63_0 = res.a3;
> +	attr->serial_number = kasprintf(GFP_KERNEL, "%016llx%016llx", uid127_64, uid63_0);
> +
> +	sdev = soc_device_register(attr);
> +	if (IS_ERR(sdev)) {
> +		err = PTR_ERR(sdev);
pr_err("%s: failed to register SoC as a device: %d\n", __func__, err);

After that we can drop the pr_err() in imx9_soc_init() and avoid
unnecessary error logs.
> +		goto soc_id;
> +	}
> +
> +	return 0;
> +
> +soc_id:
> +	kfree(attr->soc_id);
> +	kfree(attr->serial_number);
> +	kfree(attr->revision);
> +family:
> +	kfree(attr->family);
> +attr:
> +	kfree(attr);
> +	return err;
> +}
> +
> +static int __init imx9_soc_init(void)
> +{
> +	int ret = 0;
> +
> +	if (of_machine_is_compatible("fsl,imx91") ||
> +		of_machine_is_compatible("fsl,imx93") ||
> +		of_machine_is_compatible("fsl,imx95")) {
> +		ret = imx9_soc_device_register();
> +		if (ret) {
> +			pr_err("%s failed to register SoC as a device: %d\n", __func__, ret);
> +			return ret;
> +		}
After dropping the pr_err we can get the rid of the complete condition
for ret.

Thanks
> +	}
> +
> +	return ret;
> +}
> +device_initcall(imx9_soc_init);
> +
> +MODULE_AUTHOR("NXP");
> +MODULE_DESCRIPTION("NXP i.MX9 SoC");
> +MODULE_LICENSE("GPL");