drm/i915: Add self-refresh support on Sandybridge

Add the support of memory self-refresh on Sandybridge, which is now
support 3 levels of watermarks and the source of the latency values
for watermarks has changed.

On Sandybridge, the LP0 WM value is not hardcoded any more. All the
latency value is now should be extracted from MCHBAR SSKPD register.
And the MCHBAR base address is changed, too.

For the WM values, if any calculated watermark values is larger than
the maximum value that can be programmed into the associated watermark
register, that watermark must be disabled.

Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
[ickle: remove duplicate compute routines and fixup for checkpatch]
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -933,7 +933,7 @@ static int i915_sr_status(struct seq_file *m, void *unused)
 	drm_i915_private_t *dev_priv = dev->dev_private;
 	bool sr_enabled = false;
 
-	if (IS_GEN5(dev))
+	if (HAS_PCH_SPLIT(dev))
 		sr_enabled = I915_READ(WM1_LP_ILK) & WM1_LP_SR_EN;
 	else if (IS_CRESTLINE(dev) || IS_I945G(dev) || IS_I945GM(dev))
 		sr_enabled = I915_READ(FW_BLC_SELF) & FW_BLC_SELF_EN;

drivers/gpu/drm/i915/i915_reg.h

@@ -596,6 +596,8 @@
 
 #define ILK_DISPLAY_CHICKEN1	0x42000
 #define   ILK_FBCQ_DIS		(1<<22)
+#define   ILK_PABSTRETCH_DIS 	(1<<21)
+
 
 /*
  * GPIO regs
@@ -955,6 +957,8 @@
  */
 #define MCHBAR_MIRROR_BASE	0x10000
 
+#define MCHBAR_MIRROR_BASE_SNB	0x140000
+
 /** 915-945 and GM965 MCH register controlling DRAM channel access */
 #define DCC			0x10200
 #define DCC_ADDRESSING_MODE_SINGLE_CHANNEL		(0 << 0)
@@ -2346,6 +2350,40 @@
 
 #define ILK_FIFO_LINE_SIZE	64
 
+/* define the WM info on Sandybridge */
+#define SNB_DISPLAY_FIFO	128
+#define SNB_DISPLAY_MAXWM	0x7f	/* bit 16:22 */
+#define SNB_DISPLAY_DFTWM	8
+#define SNB_CURSOR_FIFO		32
+#define SNB_CURSOR_MAXWM	0x1f	/* bit 4:0 */
+#define SNB_CURSOR_DFTWM	8
+
+#define SNB_DISPLAY_SR_FIFO	512
+#define SNB_DISPLAY_MAX_SRWM	0x1ff	/* bit 16:8 */
+#define SNB_DISPLAY_DFT_SRWM	0x3f
+#define SNB_CURSOR_SR_FIFO	64
+#define SNB_CURSOR_MAX_SRWM	0x3f	/* bit 5:0 */
+#define SNB_CURSOR_DFT_SRWM	8
+
+#define SNB_FBC_MAX_SRWM	0xf	/* bit 23:20 */
+
+#define SNB_FIFO_LINE_SIZE	64
+
+
+/* the address where we get all kinds of latency value */
+#define SSKPD			0x5d10
+#define SSKPD_WM_MASK		0x3f
+#define SSKPD_WM0_SHIFT		0
+#define SSKPD_WM1_SHIFT		8
+#define SSKPD_WM2_SHIFT		16
+#define SSKPD_WM3_SHIFT		24
+
+#define SNB_LATENCY(shift)	(I915_READ(MCHBAR_MIRROR_BASE_SNB + SSKPD) >> (shift) & SSKPD_WM_MASK)
+#define SNB_READ_WM0_LATENCY()		SNB_LATENCY(SSKPD_WM0_SHIFT)
+#define SNB_READ_WM1_LATENCY()		SNB_LATENCY(SSKPD_WM1_SHIFT)
+#define SNB_READ_WM2_LATENCY()		SNB_LATENCY(SSKPD_WM2_SHIFT)
+#define SNB_READ_WM3_LATENCY()		SNB_LATENCY(SSKPD_WM3_SHIFT)
+
 /*
  * The two pipe frame counter registers are not synchronized, so
  * reading a stable value is somewhat tricky. The following code
@@ -2651,6 +2689,8 @@
 #define  ILK_VSDPFD_FULL	(1<<21)
 #define ILK_DSPCLK_GATE		0x42020
 #define  ILK_DPARB_CLK_GATE	(1<<5)
+#define  ILK_DPFD_CLK_GATE	(1<<7)
+
 /* According to spec this bit 7/8/9 of 0x42020 should be set to enable FBC */
 #define   ILK_CLK_FBC		(1<<7)
 #define   ILK_DPFC_DIS1		(1<<8)