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>

diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
index fbafed29fb8153ba404c27c8ec5183a4e82520ff..a61d9062bf7b725e5b6b8ebb5dd824b7053f1ac8 100644 (file)
--- 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 1a9f65e6ec0f043a4e45ff58c0220db5194e737d..53aab243cbd83437e60caef39ef39502bba9f5ce 100644 (file)
--- 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);