Subject: Re: [PATCH v2] soc: imx8mq: Read SOC revision from TF-A

From: Shawn Guo <[email-masked]>
Date: Mon, 4 Nov 2019 11:34:52 +0800

On Wed, Oct 30, 2019 at 01:17:39AM +0200, Leonard Crestez wrote:
> SOC revision on older imx8mq is not available in fuses so on anything
> other than B1 current code just reports "unknown".
> 
> TF-A already handles this by parsing the ROM and exposes the value
> through a SMC call. Call this instead of reimplementing the workaround
> in the kernel itself.
> 
> Signed-off-by: Leonard Crestez <[email-masked]>
> Reviewed-by: Abel Vesa <[email-masked]>
> 
> ---
> Changes since v1:
> * Add ifdef to fix build on ARM older than v7 (kbuild robot)
> Link to v1: https://patchwork.kernel.org/patch/11183813/
> 
> Alternatively a CONFIG_IMX8M_SOC config option could be created which
> depends on HAVE_ARM_SMCCC but that also requires defconfig changes.
> 
>  drivers/soc/imx/soc-imx8.c | 32 +++++++++++++++++++++++++++++---
>  1 file changed, 29 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/soc/imx/soc-imx8.c b/drivers/soc/imx/soc-imx8.c
> index fcbf745a9971..6a2916664438 100644
> --- a/drivers/soc/imx/soc-imx8.c
> +++ b/drivers/soc/imx/soc-imx8.c
> @@ -7,17 +7,20 @@
>  #include <linux/io.h>
>  #include <linux/of_address.h>
>  #include <linux/slab.h>
>  #include <linux/sys_soc.h>
>  #include <linux/platform_device.h>
> +#include <linux/arm-smccc.h>
>  #include <linux/of.h>
>  
>  #define REV_B1				0x21
>  
>  #define IMX8MQ_SW_INFO_B1		0x40
>  #define IMX8MQ_SW_MAGIC_B1		0xff0055aa
>  
> +#define IMX_SIP_GET_SOC_INFO		0xc2000006
> +
>  #define OCOTP_UID_LOW			0x410
>  #define OCOTP_UID_HIGH			0x420
>  
>  /* Same as ANADIG_DIGPROG_IMX7D */
>  #define ANADIG_DIGPROG_IMX8MM	0x800
> @@ -27,10 +30,26 @@ struct imx8_soc_data {
>  	u32 (*soc_revision)(void);
>  };
>  
>  static u64 soc_uid;
>  
> +#ifdef CONFIG_HAVE_ARM_SMCCC
> +static u32 imx8mq_soc_revision_from_atf(void)
> +{
> +	struct arm_smccc_res res;
> +
> +	arm_smccc_smc(IMX_SIP_GET_SOC_INFO, 0, 0, 0, 0, 0, 0, 0, &res);
> +
> +	if (res.a0 == SMCCC_RET_NOT_SUPPORTED)
> +		return 0;
> +	else
> +		return res.a0 & 0xff;
> +}
> +#else
> +static u32 imx8mq_soc_revision_from_atf(void) { return 0; };

We may want to have an inline for it.  I added it and applied the patch.

Shawn

> +#endif
> +
>  static u32 __init imx8mq_soc_revision(void)
>  {
>  	struct device_node *np;
>  	void __iomem *ocotp_base;
>  	u32 magic;
> @@ -41,13 +60,20 @@ static u32 __init imx8mq_soc_revision(void)
>  		goto out;
>  
>  	ocotp_base = of_iomap(np, 0);
>  	WARN_ON(!ocotp_base);
>  
> -	magic = readl_relaxed(ocotp_base + IMX8MQ_SW_INFO_B1);
> -	if (magic == IMX8MQ_SW_MAGIC_B1)
> -		rev = REV_B1;
> +	/*
> +	 * SOC revision on older imx8mq is not available in fuses so query
> +	 * the value from ATF instead.
> +	 */
> +	rev = imx8mq_soc_revision_from_atf();
> +	if (!rev) {
> +		magic = readl_relaxed(ocotp_base + IMX8MQ_SW_INFO_B1);
> +		if (magic == IMX8MQ_SW_MAGIC_B1)
> +			rev = REV_B1;
> +	}
>  
>  	soc_uid = readl_relaxed(ocotp_base + OCOTP_UID_HIGH);
>  	soc_uid <<= 32;
>  	soc_uid |= readl_relaxed(ocotp_base + OCOTP_UID_LOW);
>  
> -- 
> 2.17.1
> 

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