i2c-omap: reprogram OCP_SYSCONFIG register after reset

The I2C controller clears its OCP_SYSCONFIG register after an OCP soft reset.
Reprogram OCP_SYSCONFIG for maximum power savings on rev3.6 controllers
and beyond.  On 2430, this involves setting the module AUTOIDLE bit.
On 3430, this includes module AUTOIDLE, wakeup enable, slave smart-idle,
and considers only the module functional clock state for idle-ack.

Boot-tested on 2430SDP and 3430SDP.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Richard Woodruff <r-woodruff2@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 3ac510d..b202354 100644 (file)
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -123,11 +123,19 @@
 #define OMAP_I2C_SYSTEST_SDA_O         (1 << 0)        /* SDA line drive out */
 #endif
 
-/* I2C System Status register (OMAP_I2C_SYSS): */
-#define OMAP_I2C_SYSS_RDONE            (1 << 0)        /* Reset Done */
+/* OCP_SYSSTATUS bit definitions */
+#define SYSS_RESETDONE_MASK            (1 << 0)
+
+/* OCP_SYSCONFIG bit definitions */
+#define SYSC_CLOCKACTIVITY_MASK                (0x3 << 8)
+#define SYSC_SIDLEMODE_MASK            (0x3 << 3)
+#define SYSC_ENAWAKEUP_MASK            (1 << 2)
+#define SYSC_SOFTRESET_MASK            (1 << 1)
+#define SYSC_AUTOIDLE_MASK             (1 << 0)
+
+#define SYSC_IDLEMODE_SMART            0x2
+#define SYSC_CLOCKACTIVITY_FCLK                0x2
 
-/* I2C System Configuration Register (OMAP_I2C_SYSC): */
-#define OMAP_I2C_SYSC_SRST             (1 << 1)        /* Soft Reset */
 
 struct omap_i2c_dev {
        struct device           *dev;
@@ -239,13 +247,13 @@ static int omap_i2c_init(struct omap_i2c_dev *dev)
        unsigned long internal_clk = 0;
 
        if (dev->rev >= OMAP_I2C_REV_2) {
-               omap_i2c_write_reg(dev, OMAP_I2C_SYSC_REG, OMAP_I2C_SYSC_SRST);
+               omap_i2c_write_reg(dev, OMAP_I2C_SYSC_REG, SYSC_SOFTRESET_MASK);
                /* For some reason we need to set the EN bit before the
                 * reset done bit gets set. */
                timeout = jiffies + OMAP_I2C_TIMEOUT;
                omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN);
                while (!(omap_i2c_read_reg(dev, OMAP_I2C_SYSS_REG) &
-                        OMAP_I2C_SYSS_RDONE)) {
+                        SYSS_RESETDONE_MASK)) {
                        if (time_after(jiffies, timeout)) {
                                dev_warn(dev->dev, "timeout waiting "
                                                "for controller reset\n");
@@ -253,6 +261,26 @@ static int omap_i2c_init(struct omap_i2c_dev *dev)
                        }
                        msleep(1);
                }
+
+               /* SYSC register is cleared by the reset; rewrite it */
+               if (dev->rev == OMAP_I2C_REV_ON_2430) {
+
+                       omap_i2c_write_reg(dev, OMAP_I2C_SYSC_REG,
+                                          SYSC_AUTOIDLE_MASK);
+
+               } else if (dev->rev >= OMAP_I2C_REV_ON_3430) {
+                       u32 v;
+
+                       v = SYSC_AUTOIDLE_MASK;
+                       v |= SYSC_ENAWAKEUP_MASK;
+                       v |= (SYSC_IDLEMODE_SMART <<
+                             __ffs(SYSC_SIDLEMODE_MASK));
+                       v |= (SYSC_CLOCKACTIVITY_FCLK <<
+                             __ffs(SYSC_CLOCKACTIVITY_MASK));
+
+                       omap_i2c_write_reg(dev, OMAP_I2C_SYSC_REG, v);
+
+               }
        }
        omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, 0);