drm/i915/hwmon: Add HWMON current voltage support

Use i915 HWMON subsystem to display current input voltage.

v2:
  - Updated date and kernel version in feature description
  - Fixed review comments (Ashutosh)
v3: Use macro HWMON_CHANNEL_INFO to define hwmon channel (Guenter)
v4:
  - Fixed review comments (Ashutosh)
  - Use hwm_ prefix for static functions (Ashutosh)
v5: Added unit of voltage as millivolts (Ashutosh)
v6: KernelVersion: 6.2, Date: February 2023 in doc (Tvrtko)
v7: Change contact to intel-gfx (Rodrigo)
    GEN12_RPSTAT1 is available for all Gen12+ (Andi)
    Added Documentation/ABI/testing/sysfs-driver-intel-i915-hwmon
    to MAINTAINERS

Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Anshuman Gupta <anshuman.gupta@intel.com>
Signed-off-by: Riana Tauro <riana.tauro@intel.com>
Signed-off-by: Badal Nilawar <badal.nilawar@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Anshuman Gupta <anshuman.gupta@intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221013154526.2105579-3-ashutosh.dixit@intel.com

diff --git a/Documentation/ABI/testing/sysfs-driver-intel-i915-hwmon b/Documentation/ABI/testing/sysfs-driver-intel-i915-hwmon
new file mode 100644 (file)
index 0000000..5f4b136
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-intel-i915-hwmon
@@ -0,0 +1,7 @@
+What:          /sys/devices/.../hwmon/hwmon<i>/in0_input
+Date:          February 2023
+KernelVersion: 6.2
+Contact:       intel-gfx@lists.freedesktop.org
+Description:   RO. Current Voltage in millivolt.
+
+               Only supported for particular Intel i915 graphics platforms.

diff --git a/MAINTAINERS b/MAINTAINERS
index 4f2fa99..c03539c 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10140,6 +10140,7 @@ Q:      http://patchwork.freedesktop.org/project/intel-gfx/
 B:     https://gitlab.freedesktop.org/drm/intel/-/wikis/How-to-file-i915-bugs
 C:     irc://irc.oftc.net/intel-gfx
 T:     git git://anongit.freedesktop.org/drm-intel
+F:     Documentation/ABI/testing/sysfs-driver-intel-i915-hwmon
 F:     Documentation/gpu/i915.rst
 F:     drivers/gpu/drm/i915/
 F:     include/drm/i915*

diff --git a/drivers/gpu/drm/i915/gt/intel_gt_regs.h b/drivers/gpu/drm/i915/gt/intel_gt_regs.h
index 755a2c1..c7639ae 100644 (file)
--- a/drivers/gpu/drm/i915/gt/intel_gt_regs.h
+++ b/drivers/gpu/drm/i915/gt/intel_gt_regs.h
@@ -1516,6 +1516,9 @@
 #define VLV_RENDER_C0_COUNT                    _MMIO(0x138118)
 #define VLV_MEDIA_C0_COUNT                     _MMIO(0x13811c)
 
+#define GEN12_RPSTAT1                          _MMIO(0x1381b4)
+#define   GEN12_VOLTAGE_MASK                   REG_GENMASK(10, 0)
+
 #define GEN11_GT_INTR_DW(x)                    _MMIO(0x190018 + ((x) * 4))
 #define   GEN11_CSME                           (31)
 #define   GEN11_GUNIT                          (28)

diff --git a/drivers/gpu/drm/i915/i915_hwmon.c b/drivers/gpu/drm/i915/i915_hwmon.c
index 231552f..0253993 100644 (file)
--- a/drivers/gpu/drm/i915/i915_hwmon.c
+++ b/drivers/gpu/drm/i915/i915_hwmon.c
@@ -11,8 +11,16 @@
 #include "i915_hwmon.h"
 #include "i915_reg.h"
 #include "intel_mchbar_regs.h"
+#include "gt/intel_gt_regs.h"
+
+/*
+ * SF_* - scale factors for particular quantities according to hwmon spec.
+ * - voltage  - millivolts
+ */
+#define SF_VOLTAGE     1000
 
 struct hwm_reg {
+       i915_reg_t gt_perf_status;
 };
 
 struct hwm_drvdata {
@@ -29,14 +37,51 @@ struct i915_hwmon {
 };
 
 static const struct hwmon_channel_info *hwm_info[] = {
+       HWMON_CHANNEL_INFO(in, HWMON_I_INPUT),
        NULL
 };
 
+static umode_t
+hwm_in_is_visible(const struct hwm_drvdata *ddat, u32 attr)
+{
+       struct drm_i915_private *i915 = ddat->uncore->i915;
+
+       switch (attr) {
+       case hwmon_in_input:
+               return IS_DG1(i915) || IS_DG2(i915) ? 0444 : 0;
+       default:
+               return 0;
+       }
+}
+
+static int
+hwm_in_read(struct hwm_drvdata *ddat, u32 attr, long *val)
+{
+       struct i915_hwmon *hwmon = ddat->hwmon;
+       intel_wakeref_t wakeref;
+       u32 reg_value;
+
+       switch (attr) {
+       case hwmon_in_input:
+               with_intel_runtime_pm(ddat->uncore->rpm, wakeref)
+                       reg_value = intel_uncore_read(ddat->uncore, hwmon->rg.gt_perf_status);
+               /* HW register value in units of 2.5 millivolt */
+               *val = DIV_ROUND_CLOSEST(REG_FIELD_GET(GEN12_VOLTAGE_MASK, reg_value) * 25, 10);
+               return 0;
+       default:
+               return -EOPNOTSUPP;
+       }
+}
+
 static umode_t
 hwm_is_visible(const void *drvdata, enum hwmon_sensor_types type,
               u32 attr, int channel)
 {
+       struct hwm_drvdata *ddat = (struct hwm_drvdata *)drvdata;
+
        switch (type) {
+       case hwmon_in:
+               return hwm_in_is_visible(ddat, attr);
        default:
                return 0;
        }
@@ -46,7 +91,11 @@ static int
 hwm_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
         int channel, long *val)
 {
+       struct hwm_drvdata *ddat = dev_get_drvdata(dev);
+
        switch (type) {
+       case hwmon_in:
+               return hwm_in_read(ddat, attr, val);
        default:
                return -EOPNOTSUPP;
        }
@@ -76,6 +125,10 @@ static const struct hwmon_chip_info hwm_chip_info = {
 static void
 hwm_get_preregistration_info(struct drm_i915_private *i915)
 {
+       struct i915_hwmon *hwmon = i915->hwmon;
+
+       /* Available for all Gen12+/dGfx */
+       hwmon->rg.gt_perf_status = GEN12_RPSTAT1;
 }
 
 void i915_hwmon_register(struct drm_i915_private *i915)