i2c-pxa: Add polling transfer

Add polling I2C transfer implementation for PXA I2C. This is needed
for cases where I2C transactions have to occur at times interrups are
disabled.

Signed-off-by: Mike Rapoport <mike@compulab.co.il>
Acked-by: eric miao <eric.miao@marvell.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 121 insertions, 12 deletions

diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
index da3ecf5c591b..2598d29fd7a4 100644
--- a/drivers/i2c/busses/i2c-pxa.c
+++ b/drivers/i2c/busses/i2c-pxa.c
@@ -65,6 +65,7 @@ struct pxa_i2c {
         unsigned long           iosize;
 
         int                     irq;
+        int                     use_pio;
 };
 
 #define _IBMR(i2c)      ((i2c)->reg_base + 0)
@@ -163,6 +164,7 @@ static void i2c_pxa_show_state(struct pxa_i2c *i2c, int lno, const char *fname)
 #define eedbg(lvl, x...) do { if ((lvl) < 1) { printk(KERN_DEBUG "" x); } } while(0)
 
 static void i2c_pxa_master_complete(struct pxa_i2c *i2c, int ret);
+static irqreturn_t i2c_pxa_handler(int this_irq, void *dev_id);
 
 static void i2c_pxa_scream_blue_murder(struct pxa_i2c *i2c, const char *why)
 {
@@ -554,6 +556,71 @@ static inline void i2c_pxa_stop_message(struct pxa_i2c *i2c)
         writel(icr, _ICR(i2c));
 }
 
+static int i2c_pxa_pio_set_master(struct pxa_i2c *i2c)
+{
+        /* make timeout the same as for interrupt based functions */
+        long timeout = 2 * DEF_TIMEOUT;
+
+        /*
+         * Wait for the bus to become free.
+         */
+        while (timeout-- && readl(_ISR(i2c)) & (ISR_IBB | ISR_UB)) {
+                udelay(1000);
+                show_state(i2c);
+        }
+
+        if (timeout <= 0) {
+                show_state(i2c);
+                dev_err(&i2c->adap.dev,
+                        "i2c_pxa: timeout waiting for bus free\n");
+                return I2C_RETRY;
+        }
+
+        /*
+         * Set master mode.
+         */
+        writel(readl(_ICR(i2c)) | ICR_SCLE, _ICR(i2c));
+
+        return 0;
+}
+
+static int i2c_pxa_do_pio_xfer(struct pxa_i2c *i2c,
+                               struct i2c_msg *msg, int num)
+{
+        unsigned long timeout = 500000; /* 5 seconds */
+        int ret = 0;
+
+        ret = i2c_pxa_pio_set_master(i2c);
+        if (ret)
+                goto out;
+
+        i2c->msg = msg;
+        i2c->msg_num = num;
+        i2c->msg_idx = 0;
+        i2c->msg_ptr = 0;
+        i2c->irqlogidx = 0;
+
+        i2c_pxa_start_message(i2c);
+
+        while (timeout-- && i2c->msg_num > 0) {
+                i2c_pxa_handler(0, i2c);
+                udelay(10);
+        }
+
+        i2c_pxa_stop_message(i2c);
+
+        /*
+         * We place the return code in i2c->msg_idx.
+         */
+        ret = i2c->msg_idx;
+
+out:
+        if (timeout == 0)
+                i2c_pxa_scream_blue_murder(i2c, "timeout");
+
+        return ret;
+}
+
 /*
  * We are protected by the adapter bus mutex.
  */
@@ -610,6 +677,35 @@ static int i2c_pxa_do_xfer(struct pxa_i2c *i2c, struct i2c_msg *msg, int num)
         return ret;
 }
 
+static int i2c_pxa_pio_xfer(struct i2c_adapter *adap,
+                            struct i2c_msg msgs[], int num)
+{
+        struct pxa_i2c *i2c = adap->algo_data;
+        int ret, i;
+
+        /* If the I2C controller is disabled we need to reset it
+          (probably due to a suspend/resume destroying state). We do
+          this here as we can then avoid worrying about resuming the
+          controller before its users. */
+        if (!(readl(_ICR(i2c)) & ICR_IUE))
+                i2c_pxa_reset(i2c);
+
+        for (i = adap->retries; i >= 0; i--) {
+                ret = i2c_pxa_do_pio_xfer(i2c, msgs, num);
+                if (ret != I2C_RETRY)
+                        goto out;
+
+                if (i2c_debug)
+                        dev_dbg(&adap->dev, "Retrying transmission\n");
+                udelay(100);
+        }
+        i2c_pxa_scream_blue_murder(i2c, "exhausted retries");
+        ret = -EREMOTEIO;
+ out:
+        i2c_pxa_set_slave(i2c, ret);
+        return ret;
+}
+
 /*
  * i2c_pxa_master_complete - complete the message and wake up.
  */
@@ -621,7 +717,8 @@ static void i2c_pxa_master_complete(struct pxa_i2c *i2c, int ret)
         i2c->msg_num = 0;
         if (ret)
                 i2c->msg_idx = ret;
-        wake_up(&i2c->wait);
+        if (!i2c->use_pio)
+                wake_up(&i2c->wait);
 }
 
 static void i2c_pxa_irq_txempty(struct pxa_i2c *i2c, u32 isr)
@@ -840,6 +937,11 @@ static const struct i2c_algorithm i2c_pxa_algorithm = {
         .functionality  = i2c_pxa_functionality,
 };
 
+static const struct i2c_algorithm i2c_pxa_pio_algorithm = {
+        .master_xfer    = i2c_pxa_pio_xfer,
+        .functionality  = i2c_pxa_functionality,
+};
+
 static void i2c_pxa_enable(struct platform_device *dev)
 {
         if (cpu_is_pxa27x()) {
@@ -890,7 +992,6 @@ static int i2c_pxa_probe(struct platform_device *dev)
         }
 
         i2c->adap.owner   = THIS_MODULE;
-        i2c->adap.algo    = &i2c_pxa_algorithm;
         i2c->adap.retries = 5;
 
         spin_lock_init(&i2c->lock);
@@ -927,20 +1028,26 @@ static int i2c_pxa_probe(struct platform_device *dev)
         clk_enable(i2c->clk);
         i2c_pxa_enable(dev);
 
-        ret = request_irq(irq, i2c_pxa_handler, IRQF_DISABLED,
-                          i2c->adap.name, i2c);
-        if (ret)
-                goto ereqirq;
+        if (plat) {
+                i2c->adap.class = plat->class;
+                i2c->use_pio = plat->use_pio;
+        }
+
+        if (i2c->use_pio) {
+                i2c->adap.algo = &i2c_pxa_pio_algorithm;
+        } else {
+                i2c->adap.algo = &i2c_pxa_algorithm;
+                ret = request_irq(irq, i2c_pxa_handler, IRQF_DISABLED,
+                                  i2c->adap.name, i2c);
+                if (ret)
+                        goto ereqirq;
+        }
 
         i2c_pxa_reset(i2c);
 
         i2c->adap.algo_data = i2c;
         i2c->adap.dev.parent = &dev->dev;
 
-        if (plat) {
-                i2c->adap.class = plat->class;
-        }
-
         /*
          * If "dev->id" is negative we consider it as zero.
          * The reason to do so is to avoid sysfs names that only make
@@ -966,7 +1073,8 @@ static int i2c_pxa_probe(struct platform_device *dev)
         return 0;
 
 eadapt:
-        free_irq(irq, i2c);
+        if (!i2c->use_pio)
+                free_irq(irq, i2c);
 ereqirq:
         clk_disable(i2c->clk);
         i2c_pxa_disable(dev);
@@ -986,7 +1094,8 @@ static int i2c_pxa_remove(struct platform_device *dev)
         platform_set_drvdata(dev, NULL);
 
         i2c_del_adapter(&i2c->adap);
-        free_irq(i2c->irq, i2c);
+        if (!i2c->use_pio)
+                free_irq(i2c->irq, i2c);
 
         clk_disable(i2c->clk);
         clk_put(i2c->clk);