i2c-omap: OMAP3: PM: (re)init for every transfer to support off-mode

Because of OMAP off-mode, powerdomain can go off when I2C is idle.
Save enough state, and do a re-init for each transfer.

Additional save/restore state added by Jagadeesh Bhaskar Pakaravoor
(SYSC_REG) and Aaro Koskinen (wakeup sources.)

Also, The OMAP3430 TRM states:

"During active mode (I2Ci.I2C_CON[15] I2C_EN bit is set to 1), make no
changes to the I2Ci.I2C_SCLL and I2Ci.I2C_SCLH registers.  Changes may
result in unpredictable behavior."

Hence, the I2C_EN bit should be clearer when modifying these
registers. Please note that clearing the entire I2C_CON register to
disable the I2C module is safe, because the I2C_CON register is
re-configured for each transfer.

Signed-off-by: Jouni Hogander <jouni.hogander@nokia.com>
Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Cc: Jagadeesh Bhaskar Pakaravoor <j-pakaravoor@ti.com>
Cc: Aaro Koskinen <aaro.koskinen@nokia.com>
Cc: Jon Hunter <jon-hunter@ti.com>
Cc: Hu Tao <taohu@motorola.com>
Cc: Xiaolong Chen <A21785@motorola.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>

1 files changed, 41 insertions, 23 deletions

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 827da0858136..75bf3ad18099 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -178,6 +178,12 @@ struct omap_i2c_dev {
         unsigned                b_hw:1;         /* bad h/w fixes */
         unsigned                idle:1;
         u16                     iestate;        /* Saved interrupt register */
+        u16                     pscstate;
+        u16                     scllstate;
+        u16                     sclhstate;
+        u16                     bufstate;
+        u16                     syscstate;
+        u16                     westate;
 };
 
 static inline void omap_i2c_write_reg(struct omap_i2c_dev *i2c_dev,
@@ -230,9 +236,18 @@ static void omap_i2c_unidle(struct omap_i2c_dev *dev)
 
         clk_enable(dev->iclk);
         clk_enable(dev->fclk);
+        if (cpu_is_omap34xx()) {
+                omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, 0);
+                omap_i2c_write_reg(dev, OMAP_I2C_PSC_REG, dev->pscstate);
+                omap_i2c_write_reg(dev, OMAP_I2C_SCLL_REG, dev->scllstate);
+                omap_i2c_write_reg(dev, OMAP_I2C_SCLH_REG, dev->sclhstate);
+                omap_i2c_write_reg(dev, OMAP_I2C_BUF_REG, dev->bufstate);
+                omap_i2c_write_reg(dev, OMAP_I2C_SYSC_REG, dev->syscstate);
+                omap_i2c_write_reg(dev, OMAP_I2C_WE_REG, dev->westate);
+                omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN);
+        }
         dev->idle = 0;
-        if (dev->iestate)
-                omap_i2c_write_reg(dev, OMAP_I2C_IE_REG, dev->iestate);
+        omap_i2c_write_reg(dev, OMAP_I2C_IE_REG, dev->iestate);
 }
 
 static void omap_i2c_idle(struct omap_i2c_dev *dev)
@@ -258,7 +273,7 @@ static void omap_i2c_idle(struct omap_i2c_dev *dev)
 
 static int omap_i2c_init(struct omap_i2c_dev *dev)
 {
-        u16 psc = 0, scll = 0, sclh = 0;
+        u16 psc = 0, scll = 0, sclh = 0, buf = 0;
         u16 fsscll = 0, fssclh = 0, hsscll = 0, hssclh = 0;
         unsigned long fclk_rate = 12000000;
         unsigned long timeout;
@@ -287,24 +302,22 @@ static int omap_i2c_init(struct omap_i2c_dev *dev)
                                            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 <<
+                        dev->syscstate = SYSC_AUTOIDLE_MASK;
+                        dev->syscstate |= SYSC_ENAWAKEUP_MASK;
+                        dev->syscstate |= (SYSC_IDLEMODE_SMART <<
                               __ffs(SYSC_SIDLEMODE_MASK));
-                        v |= (SYSC_CLOCKACTIVITY_FCLK <<
+                        dev->syscstate |= (SYSC_CLOCKACTIVITY_FCLK <<
                               __ffs(SYSC_CLOCKACTIVITY_MASK));
 
-                        omap_i2c_write_reg(dev, OMAP_I2C_SYSC_REG, v);
+                        omap_i2c_write_reg(dev, OMAP_I2C_SYSC_REG,
+                                                        dev->syscstate);
                         /*
                          * Enabling all wakup sources to stop I2C freezing on
                          * WFI instruction.
                          * REVISIT: Some wkup sources might not be needed.
                          */
-                        omap_i2c_write_reg(dev, OMAP_I2C_WE_REG,
-                                                        OMAP_I2C_WE_ALL);
-
+                        dev->westate = OMAP_I2C_WE_ALL;
+                        omap_i2c_write_reg(dev, OMAP_I2C_WE_REG, dev->westate);
                 }
         }
         omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, 0);
@@ -394,23 +407,28 @@ static int omap_i2c_init(struct omap_i2c_dev *dev)
         omap_i2c_write_reg(dev, OMAP_I2C_SCLL_REG, scll);
         omap_i2c_write_reg(dev, OMAP_I2C_SCLH_REG, sclh);
 
-        if (dev->fifo_size)
-                /* Note: setup required fifo size - 1 */
-                omap_i2c_write_reg(dev, OMAP_I2C_BUF_REG,
-                                        (dev->fifo_size - 1) << 8 | /* RTRSH */
-                                        OMAP_I2C_BUF_RXFIF_CLR |
-                                        (dev->fifo_size - 1) | /* XTRSH */
-                                        OMAP_I2C_BUF_TXFIF_CLR);
+        if (dev->fifo_size) {
+                /* Note: setup required fifo size - 1. RTRSH and XTRSH */
+                buf = (dev->fifo_size - 1) << 8 | OMAP_I2C_BUF_RXFIF_CLR |
+                        (dev->fifo_size - 1) | OMAP_I2C_BUF_TXFIF_CLR;
+                omap_i2c_write_reg(dev, OMAP_I2C_BUF_REG, buf);
+        }
 
         /* Take the I2C module out of reset: */
         omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN);
 
         /* Enable interrupts */
-        omap_i2c_write_reg(dev, OMAP_I2C_IE_REG,
-                        (OMAP_I2C_IE_XRDY | OMAP_I2C_IE_RRDY |
+        dev->iestate = (OMAP_I2C_IE_XRDY | OMAP_I2C_IE_RRDY |
                         OMAP_I2C_IE_ARDY | OMAP_I2C_IE_NACK |
                         OMAP_I2C_IE_AL)  | ((dev->fifo_size) ?
-                                (OMAP_I2C_IE_RDR | OMAP_I2C_IE_XDR) : 0));
+                                (OMAP_I2C_IE_RDR | OMAP_I2C_IE_XDR) : 0);
+        omap_i2c_write_reg(dev, OMAP_I2C_IE_REG, dev->iestate);
+        if (cpu_is_omap34xx()) {
+                dev->pscstate = psc;
+                dev->scllstate = scll;
+                dev->sclhstate = sclh;
+                dev->bufstate = buf;
+        }
         return 0;
 }