arm: mach-omap2: am33xx: Enable HW Leveling in the rtc+ddr path

Enable HW leveling in RTC+DDR path. The mandate is to enable
HW leveling bit and then wait for 1 ms before accessing any
register.

Signed-off-by: Brad Griffis <bgriffis@ti.com>
Signed-off-by: Keerthy <j-keerthy@ti.com>

diff --git a/arch/arm/mach-omap2/am33xx/board.c b/arch/arm/mach-omap2/am33xx/board.c
index 62158a9..fe7b8e1 100644 (file)
--- a/arch/arm/mach-omap2/am33xx/board.c
+++ b/arch/arm/mach-omap2/am33xx/board.c
@@ -38,6 +38,14 @@
 #include <asm/omap_musb.h>
 #include <asm/davinci_rtc.h>
 
+#define AM43XX_EMIF_BASE                               0x4C000000
+#define AM43XX_SDRAM_CONFIG_OFFSET                     0x8
+#define AM43XX_SDRAM_TYPE_MASK                         0xE0000000
+#define AM43XX_SDRAM_TYPE_SHIFT                                29
+#define AM43XX_SDRAM_TYPE_DDR3                         3
+#define AM43XX_READ_WRITE_LEVELING_CTRL_OFFSET         0xDC
+#define AM43XX_RDWRLVLFULL_START                       0x80000000
+
 DECLARE_GLOBAL_DATA_PTR;
 
 int dram_init(void)
@@ -435,7 +443,7 @@ static void rtc_only(void)
        struct prm_device_inst *prm_device =
                                (struct prm_device_inst *)PRM_DEVICE_INST;
 
-       u32 scratch1;
+       u32 scratch1, sdrc;
        void (*resume_func)(void);
 
        scratch1 = readl(&rtc->scratch1);
@@ -476,6 +484,26 @@ static void rtc_only(void)
        /* Disable EMIF_DEVOFF for normal operation and to exit self-refresh */
        writel(0, &prm_device->emif_ctrl);
 
+       /* Check EMIF4D_SDRAM_CONFIG[31:29] SDRAM_TYPE */
+       /* Only perform leveling if SDRAM_TYPE = 3 (DDR3) */
+       sdrc = readl(AM43XX_EMIF_BASE + AM43XX_SDRAM_CONFIG_OFFSET);
+
+       sdrc &= AM43XX_SDRAM_TYPE_MASK;
+       sdrc >>= AM43XX_SDRAM_TYPE_SHIFT;
+
+       if (sdrc == AM43XX_SDRAM_TYPE_DDR3) {
+               writel(AM43XX_RDWRLVLFULL_START,
+                      AM43XX_EMIF_BASE +
+                      AM43XX_READ_WRITE_LEVELING_CTRL_OFFSET);
+               mdelay(1);
+
+am43xx_wait:
+               sdrc = readl(AM43XX_EMIF_BASE +
+                            AM43XX_READ_WRITE_LEVELING_CTRL_OFFSET);
+               if (sdrc == AM43XX_RDWRLVLFULL_START)
+                       goto am43xx_wait;
+       }
+
        resume_func = (void *)readl(&rtc->scratch0);
        if (resume_func)
                resume_func();