drm/i915: use GMBUS to manage i2c links
Use the GMBUS interface rather than direct bit banging to grab the EDID
over DDC (and for other forms of auxiliary communication with external
display controllers). The hope is that this method will be much faster
and more reliable than bit banging for fetching EDIDs from buggy monitors
or through switches, though we still preserve the bit banging as a
fallback in case GMBUS fails.
Based on an original patch by Jesse Barnes.
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index fd229ab..18e3749 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -583,12 +583,51 @@
# define GPIO_DATA_VAL_IN (1 << 12)
# define GPIO_DATA_PULLUP_DISABLE (1 << 13)
-#define GMBUS0 0x5100
-#define GMBUS1 0x5104
-#define GMBUS2 0x5108
-#define GMBUS3 0x510c
-#define GMBUS4 0x5110
-#define GMBUS5 0x5120
+#define GMBUS0 0x5100 /* clock/port select */
+#define GMBUS_RATE_100KHZ (0<<8)
+#define GMBUS_RATE_50KHZ (1<<8)
+#define GMBUS_RATE_400KHZ (2<<8) /* reserved on Pineview */
+#define GMBUS_RATE_1MHZ (3<<8) /* reserved on Pineview */
+#define GMBUS_HOLD_EXT (1<<7) /* 300ns hold time, rsvd on Pineview */
+#define GMBUS_PORT_DISABLED 0
+#define GMBUS_PORT_SSC 1
+#define GMBUS_PORT_VGADDC 2
+#define GMBUS_PORT_PANEL 3
+#define GMBUS_PORT_DPC 4 /* HDMIC */
+#define GMBUS_PORT_DPB 5 /* SDVO, HDMIB */
+ /* 6 reserved */
+#define GMBUS_PORT_DPD 7 /* HDMID */
+#define GMBUS_NUM_PORTS 8
+#define GMBUS1 0x5104 /* command/status */
+#define GMBUS_SW_CLR_INT (1<<31)
+#define GMBUS_SW_RDY (1<<30)
+#define GMBUS_ENT (1<<29) /* enable timeout */
+#define GMBUS_CYCLE_NONE (0<<25)
+#define GMBUS_CYCLE_WAIT (1<<25)
+#define GMBUS_CYCLE_INDEX (2<<25)
+#define GMBUS_CYCLE_STOP (4<<25)
+#define GMBUS_BYTE_COUNT_SHIFT 16
+#define GMBUS_SLAVE_INDEX_SHIFT 8
+#define GMBUS_SLAVE_ADDR_SHIFT 1
+#define GMBUS_SLAVE_READ (1<<0)
+#define GMBUS_SLAVE_WRITE (0<<0)
+#define GMBUS2 0x5108 /* status */
+#define GMBUS_INUSE (1<<15)
+#define GMBUS_HW_WAIT_PHASE (1<<14)
+#define GMBUS_STALL_TIMEOUT (1<<13)
+#define GMBUS_INT (1<<12)
+#define GMBUS_HW_RDY (1<<11)
+#define GMBUS_SATOER (1<<10)
+#define GMBUS_ACTIVE (1<<9)
+#define GMBUS3 0x510c /* data buffer bytes 3-0 */
+#define GMBUS4 0x5110 /* interrupt mask (Pineview+) */
+#define GMBUS_SLAVE_TIMEOUT_EN (1<<4)
+#define GMBUS_NAK_EN (1<<3)
+#define GMBUS_IDLE_EN (1<<2)
+#define GMBUS_HW_WAIT_EN (1<<1)
+#define GMBUS_HW_RDY_EN (1<<0)
+#define GMBUS5 0x5120 /* byte index */
+#define GMBUS_2BYTE_INDEX_EN (1<<31)
/*
* Clock control & power management