i2c: pxa: enable high speed mode for i2c bus

To enter high speed mode, following steps should be done:
1. When running in high speed mode, i2c clock rate is different
from standard mode. Clock rate must be set according to
specification first.
2. When i2c controller sends a master code and wins arbitration,
high speed mode is entered.

If you want to enable high speed mode, the following members of
platform data should be set to proper value:
1. "high_mode" should be set to "1".
2. "master_code" should be set to "8'b 0000_1xxx"(x is 0 or 1).
   If no master_code is set, set to default value 0xe.
3. "rate" should be set according to specification.

Signed-off-by: Leilei Shang <shangll@marvell.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

2 files changed, 66 insertions, 1 deletions

diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
index fbafed29fb81..a61d9062bf7b 100644
--- a/drivers/i2c/busses/i2c-pxa.c
+++ b/drivers/i2c/busses/i2c-pxa.c
@@ -110,6 +110,8 @@ MODULE_DEVICE_TABLE(platform, i2c_pxa_id_table);
 #define ICR_SADIE       (1 << 13)          /* slave address detected int enable */
 #define ICR_UR          (1 << 14)          /* unit reset */
 #define ICR_FM          (1 << 15)          /* fast mode */
+#define ICR_HS          (1 << 16)          /* High Speed mode */
+#define ICR_GPIOEN      (1 << 19)          /* enable GPIO mode for SCL in HS */
 
 #define ISR_RWM         (1 << 0)           /* read/write mode */
 #define ISR_ACKNAK      (1 << 1)           /* ack/nak status */
@@ -155,6 +157,10 @@ struct pxa_i2c {
         int                     irq;
         unsigned int            use_pio :1;
         unsigned int            fast_mode :1;
+        unsigned int            high_mode:1;
+        unsigned char           master_code;
+        unsigned long           rate;
+        bool                    highmode_enter;
 };
 
 #define _IBMR(i2c)      ((i2c)->reg_ibmr)
@@ -459,6 +465,7 @@ static void i2c_pxa_reset(struct pxa_i2c *i2c)
 
         /* set control register values */
         writel(I2C_ICR_INIT | (i2c->fast_mode ? ICR_FM : 0), _ICR(i2c));
+        writel(readl(_ICR(i2c)) | (i2c->high_mode ? ICR_HS : 0), _ICR(i2c));
 
 #ifdef CONFIG_I2C_PXA_SLAVE
         dev_info(&i2c->adap.dev, "Enabling slave mode\n");
@@ -680,6 +687,34 @@ static int i2c_pxa_pio_set_master(struct pxa_i2c *i2c)
         return 0;
 }
 
+/*
+ * PXA I2C send master code
+ * 1. Load master code to IDBR and send it.
+ *    Note for HS mode, set ICR [GPIOEN].
+ * 2. Wait until win arbitration.
+ */
+static int i2c_pxa_send_mastercode(struct pxa_i2c *i2c)
+{
+        u32 icr;
+        long timeout;
+
+        spin_lock_irq(&i2c->lock);
+        i2c->highmode_enter = true;
+        writel(i2c->master_code, _IDBR(i2c));
+
+        icr = readl(_ICR(i2c)) & ~(ICR_STOP | ICR_ALDIE);
+        icr |= ICR_GPIOEN | ICR_START | ICR_TB | ICR_ITEIE;
+        writel(icr, _ICR(i2c));
+
+        spin_unlock_irq(&i2c->lock);
+        timeout = wait_event_timeout(i2c->wait,
+                        i2c->highmode_enter == false, HZ * 1);
+
+        i2c->highmode_enter = false;
+
+        return (timeout == 0) ? I2C_RETRY : 0;
+}
+
 static int i2c_pxa_do_pio_xfer(struct pxa_i2c *i2c,
                                struct i2c_msg *msg, int num)
 {
@@ -743,6 +778,14 @@ static int i2c_pxa_do_xfer(struct pxa_i2c *i2c, struct i2c_msg *msg, int num)
                 goto out;
         }
 
+        if (i2c->high_mode) {
+                ret = i2c_pxa_send_mastercode(i2c);
+                if (ret) {
+                        dev_err(&i2c->adap.dev, "i2c_pxa_send_mastercode timeout\n");
+                        goto out;
+                        }
+        }
+
         spin_lock_irq(&i2c->lock);
 
         i2c->msg = msg;
@@ -990,11 +1033,14 @@ static irqreturn_t i2c_pxa_handler(int this_irq, void *dev_id)
                         i2c_pxa_slave_txempty(i2c, isr);
                 if (isr & ISR_IRF)
                         i2c_pxa_slave_rxfull(i2c, isr);
-        } else if (i2c->msg) {
+        } else if (i2c->msg && (!i2c->highmode_enter)) {
                 if (isr & ISR_ITE)
                         i2c_pxa_irq_txempty(i2c, isr);
                 if (isr & ISR_IRF)
                         i2c_pxa_irq_rxfull(i2c, isr);
+        } else if ((isr & ISR_ITE) && i2c->highmode_enter) {
+                i2c->highmode_enter = false;
+                wake_up(&i2c->wait);
         } else {
                 i2c_pxa_scream_blue_murder(i2c, "spurious irq");
         }
@@ -1079,6 +1125,11 @@ static int i2c_pxa_probe_pdata(struct platform_device *pdev,
         if (plat) {
                 i2c->use_pio = plat->use_pio;
                 i2c->fast_mode = plat->fast_mode;
+                i2c->high_mode = plat->high_mode;
+                i2c->master_code = plat->master_code;
+                if (!i2c->master_code)
+                        i2c->master_code = 0xe;
+                i2c->rate = plat->rate;
         }
         return 0;
 }
@@ -1151,6 +1202,7 @@ static int i2c_pxa_probe(struct platform_device *dev)
         i2c->irq = irq;
 
         i2c->slave_addr = I2C_PXA_SLAVE_ADDR;
+        i2c->highmode_enter = false;
 
         if (plat) {
 #ifdef CONFIG_I2C_PXA_SLAVE
@@ -1160,6 +1212,16 @@ static int i2c_pxa_probe(struct platform_device *dev)
                 i2c->adap.class = plat->class;
         }
 
+        if (i2c->high_mode) {
+                if (i2c->rate) {
+                        clk_set_rate(i2c->clk, i2c->rate);
+                        pr_info("i2c: <%s> set rate to %ld\n",
+                                i2c->adap.name, clk_get_rate(i2c->clk));
+                } else
+                        pr_warn("i2c: <%s> clock rate not set\n",
+                                i2c->adap.name);
+        }
+
         clk_prepare_enable(i2c->clk);
 
         if (i2c->use_pio) {
diff --git a/include/linux/i2c/pxa-i2c.h b/include/linux/i2c/pxa-i2c.h
index 1a9f65e6ec0f..53aab243cbd8 100644
--- a/include/linux/i2c/pxa-i2c.h
+++ b/include/linux/i2c/pxa-i2c.h
@@ -67,6 +67,9 @@ struct i2c_pxa_platform_data {
         unsigned int            class;
         unsigned int            use_pio :1;
         unsigned int            fast_mode :1;
+        unsigned int            high_mode:1;
+        unsigned char           master_code;
+        unsigned long           rate;
 };
 
 extern void pxa_set_i2c_info(struct i2c_pxa_platform_data *info);