[PATCH] ACPI: DPTF: Add new PCH FIVR methods

From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
To: rjw@rjwysocki.net, lenb@kernel.org
Cc: linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org,
	srinivas.pandruvada@linux.intel.com
Subject: [PATCH] ACPI: DPTF: Add new PCH FIVR methods
Date: Tue, 27 Jul 2021 09:22:40 -0700	[thread overview]
Message-ID: <20210727162240.425773-1-srinivas.pandruvada@linux.intel.com> (raw)

Some additional information is required for updating PCH FIVR values
upon WiFi channel changes.

New attributes added to the existing sysfs:
fivr_switching_freq_mhz	: Get the FIVR switching control frequency.
			  Uses ACPI method GFCS
fivr_switching_fault_status: Read the FIVR switching frequency control
			fault status. Uses ACPI method GFFS

ssc_clock_info : Presents SSC (spread spectrum clock) information for EMI
(Electro magnetic interference) control. Use ACPI method GEMI. Refer
to the description of GEMI method below.

GFFS
This ACPI method is used to read the FIVR switching frequency control
fault status.
Bits	Description
[0:0]	Fault status when set to 1
[31:1]	Reserved

GFCS
This ACPI method is used to read the FIVR switching control
frequency.
Bits	Description
[11:0]	Actual Frequency = value * XTAL_FREQ / 128
[31:12]	Reserved

GEMI
This ACPI method is used to read the programmed register value for EMI
(Electro magnetic interference) control.

Bits	Description
[7:0]	Sets clock spectrum spread percentage:
	0x00=0.2% , 0x3F=10%
	1 LSB = 0.1% increase in spread (for
	settings 0x01 thru 0x1C)
	1 LSB = 0.2% increase in spread (for
	settings 0x1E thru 0x3F)
[8]	When set to 1, enables spread
	spectrum clock
[9]	0: Triangle mode. FFC frequency
	walks around the Fcenter in a linear
	fashion
	1: Random walk mode. FFC frequency
	changes randomly within the SSC
	(Spread spectrum clock) range
[10]	0: No white noise. 1: Add white noise
	to spread waveform
[11]	When 1, future writes are ignored.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
---
This commit was merged to 5.14 next tree, but later reverted. The
problem was not in this commit but reading attributes in general. This
is fixed by prior patch "ACPI: DPTF: Fix reading of attributes"

 Documentation/ABI/testing/sysfs-platform-dptf | 40 +++++++++++++++++++
 drivers/acpi/dptf/dptf_pch_fivr.c             |  9 +++++
 2 files changed, 49 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-platform-dptf b/Documentation/ABI/testing/sysfs-platform-dptf
index 141834342a4d..53c6b1000320 100644
--- a/Documentation/ABI/testing/sysfs-platform-dptf
+++ b/Documentation/ABI/testing/sysfs-platform-dptf
@@ -111,3 +111,43 @@ Contact:	linux-acpi@vger.kernel.org
 Description:
 		(RW) The PCH FIVR (Fully Integrated Voltage Regulator) switching frequency in MHz,
 		when FIVR clock is 38.4MHz.
+
+What:		/sys/bus/platform/devices/INTC1045:00/pch_fivr_switch_frequency/fivr_switching_freq_mhz
+Date:		September, 2021
+KernelVersion:	v5.15
+Contact:	linux-acpi@vger.kernel.org
+Description:
+		(RO) Get the FIVR switching control frequency in MHz.
+
+What:		/sys/bus/platform/devices/INTC1045:00/pch_fivr_switch_frequency/fivr_switching_fault_status
+Date:		September, 2021
+KernelVersion:	v5.15
+Contact:	linux-acpi@vger.kernel.org
+Description:
+		(RO) Read the FIVR switching frequency control fault status.
+
+What:		/sys/bus/platform/devices/INTC1045:00/pch_fivr_switch_frequency/ssc_clock_info
+Date:		September, 2021
+KernelVersion:	v5.15
+Contact:	linux-acpi@vger.kernel.org
+Description:
+		(RO) Presents SSC (spread spectrum clock) information for EMI
+		(Electro magnetic interference) control. This is a bit mask.
+		Bits	Description
+		[7:0]	Sets clock spectrum spread percentage:
+			0x00=0.2% , 0x3F=10%
+			1 LSB = 0.1% increase in spread (for
+			settings 0x01 thru 0x1C)
+			1 LSB = 0.2% increase in spread (for
+			settings 0x1E thru 0x3F)
+		[8]	When set to 1, enables spread
+			spectrum clock
+		[9]	0: Triangle mode. FFC frequency
+			walks around the Fcenter in a linear
+			fashion
+			1: Random walk mode. FFC frequency
+			changes randomly within the SSC
+			(Spread spectrum clock) range
+		[10]	0: No white noise. 1: Add white noise
+			to spread waveform
+		[11]	When 1, future writes are ignored.
diff --git a/drivers/acpi/dptf/dptf_pch_fivr.c b/drivers/acpi/dptf/dptf_pch_fivr.c
index 550b9081fcbc..f4e9c2ef2f88 100644
--- a/drivers/acpi/dptf/dptf_pch_fivr.c
+++ b/drivers/acpi/dptf/dptf_pch_fivr.c
@@ -90,15 +90,24 @@ static ssize_t name##_store(struct device *dev,\
 
 PCH_FIVR_SHOW(freq_mhz_low_clock, GFC0)
 PCH_FIVR_SHOW(freq_mhz_high_clock, GFC1)
+PCH_FIVR_SHOW(ssc_clock_info, GEMI)
+PCH_FIVR_SHOW(fivr_switching_freq_mhz, GFCS)
+PCH_FIVR_SHOW(fivr_switching_fault_status, GFFS)
 PCH_FIVR_STORE(freq_mhz_low_clock, RFC0)
 PCH_FIVR_STORE(freq_mhz_high_clock, RFC1)
 
 static DEVICE_ATTR_RW(freq_mhz_low_clock);
 static DEVICE_ATTR_RW(freq_mhz_high_clock);
+static DEVICE_ATTR_RO(ssc_clock_info);
+static DEVICE_ATTR_RO(fivr_switching_freq_mhz);
+static DEVICE_ATTR_RO(fivr_switching_fault_status);
 
 static struct attribute *fivr_attrs[] = {
 	&dev_attr_freq_mhz_low_clock.attr,
 	&dev_attr_freq_mhz_high_clock.attr,
+	&dev_attr_ssc_clock_info.attr,
+	&dev_attr_fivr_switching_freq_mhz.attr,
+	&dev_attr_fivr_switching_fault_status.attr,
 	NULL
 };
 
-- 
2.31.1

