[PATCH 2/2] drm/i915/gmbus: Add Wa_16025573575 for PTL for bit-bashing

[Ankit Nautiyal]

As per Wa_16025573575 for PTL, set the GPIO masks bit before starting
bit-bashing and maintain value through the bit-bashing sequence.
After bit-bashing sequence is done, clear the GPIO masks bits.

v2:
-Use new helper for display workarounds. (Jani)
-Use a separate if-block for the workaround. (Gustavo)

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
---
 .../gpu/drm/i915/display/intel_display_wa.c   |  7 ++++
 .../gpu/drm/i915/display/intel_display_wa.h   |  1 +
 drivers/gpu/drm/i915/display/intel_gmbus.c    | 34 +++++++++++++++++--
 3 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display_wa.c b/drivers/gpu/drm/i915/display/intel_display_wa.c
index f5e8d58d9a68..12d1df5981f7 100644
--- a/drivers/gpu/drm/i915/display/intel_display_wa.c
+++ b/drivers/gpu/drm/i915/display/intel_display_wa.c
@@ -42,11 +42,18 @@ void intel_display_wa_apply(struct intel_display *display)
 		gen11_display_wa_apply(display);
 }
 
+static bool intel_display_needs_wa_16025573575(struct intel_display *display)
+{
+	return DISPLAY_VER(display) == 30;
+}
+
 bool __intel_display_wa(struct intel_display *display, enum intel_display_wa wa)
 {
 	switch (wa) {
 	case INTEL_DISPLAY_WA_16023588340:
 		return intel_display_needs_wa_16023588340(display);
+	case INTEL_DISPLAY_WA_16025573575:
+		return intel_display_needs_wa_16025573575(display);
 	default:
 		drm_WARN(display->drm, 1, "Missing Wa number: %d\n", wa);
 		break;
diff --git a/drivers/gpu/drm/i915/display/intel_display_wa.h b/drivers/gpu/drm/i915/display/intel_display_wa.h
index 146ee70d66f7..d3d241992e55 100644
--- a/drivers/gpu/drm/i915/display/intel_display_wa.h
+++ b/drivers/gpu/drm/i915/display/intel_display_wa.h
@@ -23,6 +23,7 @@ bool intel_display_needs_wa_16023588340(struct intel_display *display);
 
 enum intel_display_wa {
 	INTEL_DISPLAY_WA_16023588340,
+	INTEL_DISPLAY_WA_16025573575,
 };
 
 bool __intel_display_wa(struct intel_display *display, enum intel_display_wa wa);
diff --git a/drivers/gpu/drm/i915/display/intel_gmbus.c b/drivers/gpu/drm/i915/display/intel_gmbus.c
index 0d73f32fe7f1..95cab11c9cde 100644
--- a/drivers/gpu/drm/i915/display/intel_gmbus.c
+++ b/drivers/gpu/drm/i915/display/intel_gmbus.c
@@ -39,6 +39,7 @@
 #include "intel_de.h"
 #include "intel_display_regs.h"
 #include "intel_display_types.h"
+#include "intel_display_wa.h"
 #include "intel_gmbus.h"
 #include "intel_gmbus_regs.h"
 
@@ -241,11 +242,18 @@ static u32 get_reserved(struct intel_gmbus *bus)
 {
 	struct intel_display *display = bus->display;
 	u32 reserved = 0;
+	u32 preserve_bits = 0;
 
 	/* On most chips, these bits must be preserved in software. */
 	if (!display->platform.i830 && !display->platform.i845g)
-		reserved = intel_de_read_notrace(display, bus->gpio_reg) &
-			(GPIO_DATA_PULLUP_DISABLE | GPIO_CLOCK_PULLUP_DISABLE);
+		preserve_bits |= GPIO_DATA_PULLUP_DISABLE | GPIO_CLOCK_PULLUP_DISABLE;
+
+	/* PTL: Wa_16025573575: the masks bits need to be preserved through out */
+	if (intel_display_wa(display, 16025573575))
+		preserve_bits |= GPIO_CLOCK_DIR_MASK | GPIO_CLOCK_VAL_MASK |
+				 GPIO_DATA_DIR_MASK | GPIO_DATA_VAL_MASK;
+
+	reserved = intel_de_read_notrace(display, bus->gpio_reg) & preserve_bits;
 
 	return reserved;
 }
@@ -308,6 +316,22 @@ static void set_data(void *data, int state_high)
 	intel_de_posting_read(display, bus->gpio_reg);
 }
 
+static void
+ptl_handle_mask_bits(struct intel_gmbus *bus, bool set)
+{
+	struct intel_display *display = bus->display;
+	u32 reg_val = intel_de_read_notrace(display, bus->gpio_reg);
+	u32 mask_bits = GPIO_CLOCK_DIR_MASK | GPIO_CLOCK_VAL_MASK |
+			GPIO_DATA_DIR_MASK | GPIO_DATA_VAL_MASK;
+	if (set)
+		reg_val |= mask_bits;
+	else
+		reg_val &= ~mask_bits;
+
+	intel_de_write_notrace(display, bus->gpio_reg, reg_val);
+	intel_de_posting_read(display, bus->gpio_reg);
+}
+
 static int
 intel_gpio_pre_xfer(struct i2c_adapter *adapter)
 {
@@ -319,6 +343,9 @@ intel_gpio_pre_xfer(struct i2c_adapter *adapter)
 	if (display->platform.pineview)
 		pnv_gmbus_clock_gating(display, false);
 
+	if (intel_display_wa(display, 16025573575))
+		ptl_handle_mask_bits(bus, true);
+
 	set_data(bus, 1);
 	set_clock(bus, 1);
 	udelay(I2C_RISEFALL_TIME);
@@ -336,6 +363,9 @@ intel_gpio_post_xfer(struct i2c_adapter *adapter)
 
 	if (display->platform.pineview)
 		pnv_gmbus_clock_gating(display, true);
+
+	if (intel_display_wa(display, 16025573575))
+		ptl_handle_mask_bits(bus, false);
 }
 
 static void
-- 
2.45.2