linux-kernel - Re: [PATCH v2] hwmon: xgene: Support hwmon v2

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Date:   Tue, 10 Oct 2017 20:54:10 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Hoan Tran <hotran@....com>, Jean Delvare <jdelvare@...e.com>
Cc:     linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
        lho@....com, kdinh@....com, patches@....com
Subject: Re: [PATCH v2] hwmon: xgene: Support hwmon v2

On 10/10/2017 05:10 PM, Hoan Tran wrote:
> This patch supports xgene-hwmon v2 which uses the non-cachable memory
> as the PCC shared memory.
> 
> Signed-off-by: Hoan Tran <hotran@....com>
> ---
> 
> v2
>   - Map PCC shared mem by ioremap() in case hwmon is v2
> 

So I assume you expect me to replace the (already accepted) v1
of this patch with this one ?

Assuming the change is needed, I really have to ask: Has this version
of the patch been tested ?

>   drivers/hwmon/xgene-hwmon.c | 52 +++++++++++++++++++++++++++++++++++----------
>   1 file changed, 41 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/hwmon/xgene-hwmon.c b/drivers/hwmon/xgene-hwmon.c
> index 9c0dbb8..52be7cd 100644
> --- a/drivers/hwmon/xgene-hwmon.c
> +++ b/drivers/hwmon/xgene-hwmon.c
> @@ -91,6 +91,11 @@
>   #define to_xgene_hwmon_dev(cl)		\
>   	container_of(cl, struct xgene_hwmon_dev, mbox_client)
>   
> +enum xgene_hwmon_version {
> +	XGENE_HWMON_V1 = 0,
> +	XGENE_HWMON_V2 = 1,
> +};
> +
>   struct slimpro_resp_msg {
>   	u32 msg;
>   	u32 param1;
> @@ -99,6 +104,7 @@ struct slimpro_resp_msg {
>   
>   struct xgene_hwmon_dev {
>   	struct device		*dev;
> +	int			version;
>   	struct mbox_chan	*mbox_chan;
>   	struct mbox_client	mbox_client;
>   	int			mbox_idx;
> @@ -135,6 +141,15 @@ static u16 xgene_word_tst_and_clr(u16 *addr, u16 mask)
>   	return ret;
>   }
>   
> +static void *xgene_pcc_ioremap(struct xgene_hwmon_dev *ctx,
> +			       phys_addr_t phys, size_t size)
> +{
> +	if (ctx->version == XGENE_HWMON_V2)
> +		return (void __force *)ioremap(phys, size);
> +
Is that typecast really necessary ?

> +	return memremap(phys, size, MEMREMAP_WB);
> +}
> +
>   static int xgene_hwmon_pcc_rd(struct xgene_hwmon_dev *ctx, u32 *msg)
>   {
>   	struct acpi_pcct_shared_memory *generic_comm_base = ctx->pcc_comm_addr;
> @@ -609,6 +624,15 @@ static void xgene_hwmon_tx_done(struct mbox_client *cl, void *msg, int ret)
>   	}
>   }
>   
> +#ifdef CONFIG_ACPI
> +static const struct acpi_device_id xgene_hwmon_acpi_match[] = {
> +	{"APMC0D29", XGENE_HWMON_V1},
> +	{"APMC0D8A", XGENE_HWMON_V2},
> +	{},
> +};
> +MODULE_DEVICE_TABLE(acpi, xgene_hwmon_acpi_match);
> +#endif
> +
>   static int xgene_hwmon_probe(struct platform_device *pdev)
>   {
>   	struct xgene_hwmon_dev *ctx;
> @@ -623,6 +647,20 @@ static int xgene_hwmon_probe(struct platform_device *pdev)
>   	platform_set_drvdata(pdev, ctx);
>   	cl = &ctx->mbox_client;
>   
> +#ifdef CONFIG_ACPI
> +	ctx->version = -EINVAL;
> +	if (ACPI_COMPANION(&pdev->dev)) {
> +		const struct acpi_device_id *acpi_id;
> +
> +		acpi_id = acpi_match_device(xgene_hwmon_acpi_match, &pdev->dev);
> +		if (acpi_id)
> +			ctx->version = (int)acpi_id->driver_data;
> +	}
> +
> +	if (ctx->version < 0)
> +		return -ENODEV;

This doesn't make sense. Just return EINVAL if acpi_id is 0 above. There
is no need to assign a negative value to ctx->version.

I also don't see why ctx->version is necessary in the first place. In reality
it is just a parameter to xgene_pcc_ioremap(). Which I think should be inline
and not a separate function.

> +#endif

What if ACPI is enabled in the build but the system is running on HW which
does not support ACPI ? Is that guaranteed to never happen ? Why not use
acpi_disabled instead ?

> +
>   	spin_lock_init(&ctx->kfifo_lock);
>   	mutex_init(&ctx->rd_mutex);
>   
> @@ -690,9 +728,9 @@ static int xgene_hwmon_probe(struct platform_device *pdev)
>   		 */
>   		ctx->comm_base_addr = cppc_ss->base_address;
>   		if (ctx->comm_base_addr) {
> -			ctx->pcc_comm_addr = memremap(ctx->comm_base_addr,
> -							cppc_ss->length,
> -							MEMREMAP_WB);
> +			ctx->pcc_comm_addr = xgene_pcc_ioremap(ctx,
> +						ctx->comm_base_addr,
> +						cppc_ss->length);

Inline, please. The extra function adds more complexity than it is worth.

>   		} else {
>   			dev_err(&pdev->dev, "Failed to get PCC comm region\n");
>   			rc = -ENODEV;
> @@ -758,14 +796,6 @@ static int xgene_hwmon_remove(struct platform_device *pdev)
>   	return 0;
>   }
>   
> -#ifdef CONFIG_ACPI
> -static const struct acpi_device_id xgene_hwmon_acpi_match[] = {
> -	{"APMC0D29", 0},
> -	{},
> -};
> -MODULE_DEVICE_TABLE(acpi, xgene_hwmon_acpi_match);
> -#endif
> -
>   static const struct of_device_id xgene_hwmon_of_match[] = {
>   	{.compatible = "apm,xgene-slimpro-hwmon"},
>   	{}
>