[PATCH v2] drm/xe/hwmon: Update xe hwmon with couple of fixes

[Karthik Poosa]

Fix potential overflows with upcasting.
Initialize variables which were being used uninitialized.

v2:
 - Rebase.
 - In xe_hwmon_process_reg, set argument 'value' to 0 on failure.
   With this change caller function need not initialize value to 0.

Fixes: 4446fcf220ce ("drm/xe/hwmon: Expose power1_max_interval")
Signed-off-by: Karthik Poosa <karthik.poosa at intel.com>
Reviewed-by: Anshuman Gupta <anshuman.gupta at intel.com>
---
 drivers/gpu/drm/xe/xe_hwmon.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_hwmon.c b/drivers/gpu/drm/xe/xe_hwmon.c
index 7e8caac838e0..bc1bc73749c1 100644
--- a/drivers/gpu/drm/xe/xe_hwmon.c
+++ b/drivers/gpu/drm/xe/xe_hwmon.c
@@ -129,8 +129,10 @@ static void xe_hwmon_process_reg(struct xe_hwmon *hwmon, enum xe_hwmon_reg hwmon
 
 	reg.raw = xe_hwmon_get_reg(hwmon, hwmon_reg, channel);
 
-	if (!reg.raw)
+	if (!reg.raw) {
+		*value = 0;
 		return;
+	}
 
 	switch (operation) {
 	case REG_READ32:
@@ -143,6 +145,7 @@ static void xe_hwmon_process_reg(struct xe_hwmon *hwmon, enum xe_hwmon_reg hwmon
 		*value = xe_mmio_read64_2x32(hwmon->gt, reg);
 		break;
 	default:
+		*value = 0;
 		drm_warn(&gt_to_xe(hwmon->gt)->drm, "Invalid xe hwmon reg operation: %d\n",
 			 operation);
 		break;
@@ -298,7 +301,7 @@ xe_hwmon_power_max_interval_show(struct device *dev, struct device_attribute *at
 	 * As y can be < 2, we compute tau4 = (4 | x) << y
 	 * and then add 2 when doing the final right shift to account for units
 	 */
-	tau4 = ((1 << x_w) | x) << y;
+	tau4 = (u64)((1 << x_w) | x) << y;
 
 	/* val in hwmon interface units (millisec) */
 	out = mul_u64_u32_shr(tau4, SF_TIME, hwmon->scl_shift_time + x_w);
@@ -339,7 +342,7 @@ xe_hwmon_power_max_interval_store(struct device *dev, struct device_attribute *a
 	r = FIELD_PREP(PKG_MAX_WIN, PKG_MAX_WIN_DEFAULT);
 	x = REG_FIELD_GET(PKG_MAX_WIN_X, r);
 	y = REG_FIELD_GET(PKG_MAX_WIN_Y, r);
-	tau4 = ((1 << x_w) | x) << y;
+	tau4 = (u64)((1 << x_w) | x) << y;
 	max_win = mul_u64_u32_shr(tau4, SF_TIME, hwmon->scl_shift_time + x_w);
 
 	if (val > max_win)
-- 
2.25.1