[PATCH] 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.

Signed-off-by: Ankit Nautiyal <ankit.k.nauti...@intel.com>
---
 drivers/gpu/drm/i915/display/intel_gmbus.c | 38 +++++++++++++++++++---
 1 file changed, 34 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_gmbus.c 
b/drivers/gpu/drm/i915/display/intel_gmbus.c
index 0d73f32fe7f1..c96167c70228 100644
--- a/drivers/gpu/drm/i915/display/intel_gmbus.c
+++ b/drivers/gpu/drm/i915/display/intel_gmbus.c
@@ -242,10 +242,17 @@ static u32 get_reserved(struct intel_gmbus *bus)
        struct intel_display *display = bus->display;
        u32 reserved = 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);
+       if (!display->platform.i830 && !display->platform.i845g) {
+               /* On most chips, these bits must be preserved in software. */
+               u32 preserve_bits = GPIO_DATA_PULLUP_DISABLE | 
GPIO_CLOCK_PULLUP_DISABLE;
+
+               /* PTL: Wa_16025573575: the masks bits need to be preserved 
through out */
+               if (DISPLAY_VER(display) == 30)
+                       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 +315,23 @@ static void set_data(void *data, int state_high)
        intel_de_posting_read(display, bus->gpio_reg);
 }
 
+/* PTL: Wa_16025573575 */
+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 (DISPLAY_VER(display) == 30)
+               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 (DISPLAY_VER(display) == 30)
+               ptl_handle_mask_bits(bus, false);
 }
 
 static void
-- 
2.45.2