linux-kernel - Re: [PATCH v2 2/4] platform/x86: intel_pmc

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Date:   Fri, 17 Mar 2017 10:11:59 -0700
From:   sathyanarayanan kuppuswamy 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Rajneesh Bhardwaj <rajneesh.bhardwaj@...el.com>
Cc:     andy@...radead.org, qipeng.zha@...el.com, dvhart@...radead.org,
        david.e.box@...ux.intel.com, platform-driver-x86@...r.kernel.org,
        linux-kernel@...r.kernel.org, shanth.murthy@...el.com
Subject: Re: [PATCH v2 2/4] platform/x86: intel_pmc_ipc: Add pmc gcr
 read/write api's

Hi,


On 03/17/2017 04:26 AM, Rajneesh Bhardwaj wrote:
> On Thu, Mar 16, 2017 at 05:41:34PM -0700, Kuppuswamy Sathyanarayanan wrote:
>> This patch adds API's to read/write PMC GC registers.
>> PMC dependent devices like iTCO_WDT, Telemetry has requirement
>> to acces GCR registers. These API's can be used for this
>> purpose.
>>
>> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
>> ---
>>   arch/x86/include/asm/intel_pmc_ipc.h | 16 ++++++++++++++++
>>   drivers/platform/x86/intel_pmc_ipc.c | 14 ++++++++++++++
>>   2 files changed, 30 insertions(+)
>>
>> diff --git a/arch/x86/include/asm/intel_pmc_ipc.h b/arch/x86/include/asm/intel_pmc_ipc.h
>> index 4291b6a..017429d 100644
>> --- a/arch/x86/include/asm/intel_pmc_ipc.h
>> +++ b/arch/x86/include/asm/intel_pmc_ipc.h
>> @@ -23,6 +23,10 @@
>>   #define IPC_ERR_EMSECURITY		6
>>   #define IPC_ERR_UNSIGNEDKERNEL		7
>>   
>> +/* GCR reg offsets from gcr base*/
>> +#define PMC_GCR_PRSTS_REG		0x00
> remove.
Will remove it in next series.
>
>> +#define PMC_GCR_PMC_CFG_REG		0x08
>> +
>>   #if IS_ENABLED(CONFIG_INTEL_PMC_IPC)
>>   
>>   int intel_pmc_ipc_simple_command(int cmd, int sub);
>> @@ -31,6 +35,8 @@ int intel_pmc_ipc_raw_cmd(u32 cmd, u32 sub, u8 *in, u32 inlen,
>>   int intel_pmc_ipc_command(u32 cmd, u32 sub, u8 *in, u32 inlen,
>>   		u32 *out, u32 outlen);
>>   int intel_pmc_s0ix_counter_read(u64 *data);
>> +u32 intel_pmc_gcr_read(u32 offset);
> consider changing the signature to read data as out param and use return
> value for better error handling since exported API can be called from
> anywhere in the kernel.
I can add check to make sure offset is within GCR range.
>
>> +void intel_pmc_gcr_write(u32 offset, u32 data);
> ditto.
Same as above.
>
>>   
>>   #else
>>   
>> @@ -56,6 +62,16 @@ static inline int intel_pmc_s0ix_counter_read(u64 *data)
>>   	return -EINVAL;
>>   }
>>   
>> +static inline u32 intel_pmc_gcr_read(u32 offset)
>> +{
>> +	return -EINVAL;
>> +}
>> +
> samew as above.
Same as above.
>
>> +static inline void intel_pmc_gcr_write(u32 offset, u32 data)
>> +{
>> +	return;
>> +}
>> +
> ditto.
Same as above.
>
>>   #endif /*CONFIG_INTEL_PMC_IPC*/
>>   
>>   #endif
>> diff --git a/drivers/platform/x86/intel_pmc_ipc.c b/drivers/platform/x86/intel_pmc_ipc.c
>> index 0a33592..12018f3 100644
>> --- a/drivers/platform/x86/intel_pmc_ipc.c
>> +++ b/drivers/platform/x86/intel_pmc_ipc.c
>> @@ -127,6 +127,7 @@ static struct intel_pmc_ipc_dev {
>>   
>>   	/* gcr */
>>   	resource_size_t gcr_base;
>> +	void __iomem *gcr_mem_base;
>>   	int gcr_size;
>>   	bool has_gcr_regs;
>>   
>> @@ -199,6 +200,18 @@ static inline u64 gcr_data_readq(u32 offset)
>>   	return readq(ipcdev.ipc_base + offset);
>>   }
>>   
>> +u32 intel_pmc_gcr_read(u32 offset)
>> +{
>> +	return readl(ipcdev.gcr_mem_base + offset);
>> +}
> what happens when this is called with a wrong offset on IPC enabled
> platforms?
>
>> +EXPORT_SYMBOL_GPL(intel_pmc_gcr_read);
>> +
>> +void intel_pmc_gcr_write(u32 offset, u32 data)
>> +{
>> +	writel(data, ipcdev.gcr_mem_base + offset);
>> +}
> same as above.
>
>> +EXPORT_SYMBOL_GPL(intel_pmc_gcr_write);
>> +
>>   static int intel_pmc_ipc_check_status(void)
>>   {
>>   	int status;
>> @@ -747,6 +760,7 @@ static int ipc_plat_get_res(struct platform_device *pdev)
>>   	ipcdev.ipc_base = addr;
>>   
>>   	ipcdev.gcr_base = res->start + PLAT_RESOURCE_GCR_OFFSET;
>> +	ipcdev.gcr_mem_base = addr + PLAT_RESOURCE_GCR_OFFSET;
>>   	ipcdev.gcr_size = PLAT_RESOURCE_GCR_SIZE;
>>   	dev_info(&pdev->dev, "ipc res: %pR\n", res);
>>   
>> -- 
>> 2.7.4
>>

-- 
Sathyanarayanan Kuppuswamy
Android kernel developer