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 da3ecf5..2598d29 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);