Merge branch 'i2c/for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux

Pull i2c updates from Wolfram Sang:
 "Highlights:

   - new drivers for Intel ismt & Broadcom bcm2835
   - a number of drivers got support for more variants and mostly got
     cleaned up on the way (sis630, i801, at91, tegra, designware)
   - i2c got rid of all *_set_drvdata(..., NULL) on remove/probe failure
   - removed the i2c_smbus_process_call from the core since there are no
     users
   - mxs can now switch between PIO and DMA depending on the message
     size and the bus speed can now be arbitrary

  In addition, there is the usual bunch of fixes, cleanups, devm_*
  conversions, etc"

Fixed conflict (and buggy devm_* conversion) in i2c-s3c2410.c

* 'i2c/for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux: (39 commits)
  i2c: Remove unneeded xxx_set_drvdata(..., NULL) calls
  i2c: pxa: remove incorrect __exit annotations
  i2c: ocores: Fix pointer to integer cast warning
  i2c: tegra: remove warning dump if timeout happen in transfer
  i2c: fix i2c-ismt.c printk format warning
  i2c: i801: Add Device IDs for Intel Wellsburg PCH
  i2c: add bcm2835 driver
  i2c: ismt: Add Seth and Myself as maintainers
  i2c: sis630: checkpatch cleanup
  i2c: sis630: display unsigned hex
  i2c: sis630: use hex to constants for SMBus commands
  i2c: sis630: fix behavior after collision
  i2c: sis630: clear sticky bits
  i2c: sis630: Add SIS964 support
  i2c: isch: Add module parameter for backbone clock rate if divider is unset
  i2c: at91: fix unsed variable warning when building with !CONFIG_OF
  i2c: Adding support for Intel iSMT SMBus 2.0 host controller
  i2c: sh_mobile: don't send a stop condition by default inside transfers
  i2c: sh_mobile: eliminate an open-coded "goto" loop
  i2c: sh_mobile: fix timeout error handling
  ...

1 files changed, 218 insertions, 54 deletions

diff --git a/drivers/i2c/busses/i2c-mxs.c b/drivers/i2c/busses/i2c-mxs.c
index d6abaf2cf2e..120f2464669 100644
--- a/drivers/i2c/busses/i2c-mxs.c
+++ b/drivers/i2c/busses/i2c-mxs.c
@@ -39,6 +39,7 @@
 #define MXS_I2C_CTRL0_SET	(0x04)
 
 #define MXS_I2C_CTRL0_SFTRST			0x80000000
+#define MXS_I2C_CTRL0_RUN			0x20000000
 #define MXS_I2C_CTRL0_SEND_NAK_ON_LAST		0x02000000
 #define MXS_I2C_CTRL0_RETAIN_CLOCK		0x00200000
 #define MXS_I2C_CTRL0_POST_SEND_STOP		0x00100000
@@ -64,6 +65,13 @@
 #define MXS_I2C_CTRL1_SLAVE_STOP_IRQ		0x02
 #define MXS_I2C_CTRL1_SLAVE_IRQ			0x01
 
+#define MXS_I2C_DATA		(0xa0)
+
+#define MXS_I2C_DEBUG0		(0xb0)
+#define MXS_I2C_DEBUG0_CLR	(0xb8)
+
+#define MXS_I2C_DEBUG0_DMAREQ	0x80000000
+
 #define MXS_I2C_IRQ_MASK	(MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ | \
 				 MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ | \
 				 MXS_I2C_CTRL1_EARLY_TERM_IRQ | \
@@ -85,35 +93,6 @@
 #define MXS_CMD_I2C_READ	(MXS_I2C_CTRL0_SEND_NAK_ON_LAST | \
 				 MXS_I2C_CTRL0_MASTER_MODE)
 
-struct mxs_i2c_speed_config {
-	uint32_t	timing0;
-	uint32_t	timing1;
-	uint32_t	timing2;
-};
-
-/*
- * Timing values for the default 24MHz clock supplied into the i2c block.
- *
- * The bus can operate at 95kHz or at 400kHz with the following timing
- * register configurations. The 100kHz mode isn't present because it's
- * values are not stated in the i.MX233/i.MX28 datasheet. The 95kHz mode
- * shall be close enough replacement. Therefore when the bus is configured
- * for 100kHz operation, 95kHz timing settings are actually loaded.
- *
- * For details, see i.MX233 [25.4.2 - 25.4.4] and i.MX28 [27.5.2 - 27.5.4].
- */
-static const struct mxs_i2c_speed_config mxs_i2c_95kHz_config = {
-	.timing0	= 0x00780030,
-	.timing1	= 0x00800030,
-	.timing2	= 0x00300030,
-};
-
-static const struct mxs_i2c_speed_config mxs_i2c_400kHz_config = {
-	.timing0	= 0x000f0007,
-	.timing1	= 0x001f000f,
-	.timing2	= 0x00300030,
-};
-
 /**
  * struct mxs_i2c_dev - per device, private MXS-I2C data
  *
@@ -129,7 +108,9 @@ struct mxs_i2c_dev {
 	struct completion cmd_complete;
 	int cmd_err;
 	struct i2c_adapter adapter;
-	const struct mxs_i2c_speed_config *speed;
+
+	uint32_t timing0;
+	uint32_t timing1;
 
 	/* DMA support components */
 	int				dma_channel;
@@ -145,9 +126,16 @@ static void mxs_i2c_reset(struct mxs_i2c_dev *i2c)
 {
 	stmp_reset_block(i2c->regs);
 
-	writel(i2c->speed->timing0, i2c->regs + MXS_I2C_TIMING0);
-	writel(i2c->speed->timing1, i2c->regs + MXS_I2C_TIMING1);
-	writel(i2c->speed->timing2, i2c->regs + MXS_I2C_TIMING2);
+	/*
+	 * Configure timing for the I2C block. The I2C TIMING2 register has to
+	 * be programmed with this particular magic number. The rest is derived
+	 * from the XTAL speed and requested I2C speed.
+	 *
+	 * For details, see i.MX233 [25.4.2 - 25.4.4] and i.MX28 [27.5.2 - 27.5.4].
+	 */
+	writel(i2c->timing0, i2c->regs + MXS_I2C_TIMING0);
+	writel(i2c->timing1, i2c->regs + MXS_I2C_TIMING1);
+	writel(0x00300030, i2c->regs + MXS_I2C_TIMING2);
 
 	writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
 }
@@ -298,6 +286,135 @@ write_init_pio_fail:
 	return -EINVAL;
 }
 
+static int mxs_i2c_pio_wait_dmareq(struct mxs_i2c_dev *i2c)
+{
+	unsigned long timeout = jiffies + msecs_to_jiffies(1000);
+
+	while (!(readl(i2c->regs + MXS_I2C_DEBUG0) &
+		MXS_I2C_DEBUG0_DMAREQ)) {
+		if (time_after(jiffies, timeout))
+			return -ETIMEDOUT;
+		cond_resched();
+	}
+
+	writel(MXS_I2C_DEBUG0_DMAREQ, i2c->regs + MXS_I2C_DEBUG0_CLR);
+
+	return 0;
+}
+
+static int mxs_i2c_pio_wait_cplt(struct mxs_i2c_dev *i2c)
+{
+	unsigned long timeout = jiffies + msecs_to_jiffies(1000);
+
+	/*
+	 * We do not use interrupts in the PIO mode. Due to the
+	 * maximum transfer length being 8 bytes in PIO mode, the
+	 * overhead of interrupt would be too large and this would
+	 * neglect the gain from using the PIO mode.
+	 */
+
+	while (!(readl(i2c->regs + MXS_I2C_CTRL1) &
+		MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ)) {
+		if (time_after(jiffies, timeout))
+			return -ETIMEDOUT;
+		cond_resched();
+	}
+
+	writel(MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ,
+		i2c->regs + MXS_I2C_CTRL1_CLR);
+
+	return 0;
+}
+
+static int mxs_i2c_pio_setup_xfer(struct i2c_adapter *adap,
+			struct i2c_msg *msg, uint32_t flags)
+{
+	struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
+	uint32_t addr_data = msg->addr << 1;
+	uint32_t data = 0;
+	int i, shifts_left, ret;
+
+	/* Mute IRQs coming from this block. */
+	writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_CLR);
+
+	if (msg->flags & I2C_M_RD) {
+		addr_data |= I2C_SMBUS_READ;
+
+		/* SELECT command. */
+		writel(MXS_I2C_CTRL0_RUN | MXS_CMD_I2C_SELECT,
+			i2c->regs + MXS_I2C_CTRL0);
+
+		ret = mxs_i2c_pio_wait_dmareq(i2c);
+		if (ret)
+			return ret;
+
+		writel(addr_data, i2c->regs + MXS_I2C_DATA);
+
+		ret = mxs_i2c_pio_wait_cplt(i2c);
+		if (ret)
+			return ret;
+
+		/* READ command. */
+		writel(MXS_I2C_CTRL0_RUN | MXS_CMD_I2C_READ | flags |
+			MXS_I2C_CTRL0_XFER_COUNT(msg->len),
+			i2c->regs + MXS_I2C_CTRL0);
+
+		for (i = 0; i < msg->len; i++) {
+			if ((i & 3) == 0) {
+				ret = mxs_i2c_pio_wait_dmareq(i2c);
+				if (ret)
+					return ret;
+				data = readl(i2c->regs + MXS_I2C_DATA);
+			}
+			msg->buf[i] = data & 0xff;
+			data >>= 8;
+		}
+	} else {
+		addr_data |= I2C_SMBUS_WRITE;
+
+		/* WRITE command. */
+		writel(MXS_I2C_CTRL0_RUN | MXS_CMD_I2C_WRITE | flags |
+			MXS_I2C_CTRL0_XFER_COUNT(msg->len + 1),
+			i2c->regs + MXS_I2C_CTRL0);
+
+		/*
+		 * The LSB of data buffer is the first byte blasted across
+		 * the bus. Higher order bytes follow. Thus the following
+		 * filling schematic.
+		 */
+		data = addr_data << 24;
+		for (i = 0; i < msg->len; i++) {
+			data >>= 8;
+			data |= (msg->buf[i] << 24);
+			if ((i & 3) == 2) {
+				ret = mxs_i2c_pio_wait_dmareq(i2c);
+				if (ret)
+					return ret;
+				writel(data, i2c->regs + MXS_I2C_DATA);
+			}
+		}
+
+		shifts_left = 24 - (i & 3) * 8;
+		if (shifts_left) {
+			data >>= shifts_left;
+			ret = mxs_i2c_pio_wait_dmareq(i2c);
+			if (ret)
+				return ret;
+			writel(data, i2c->regs + MXS_I2C_DATA);
+		}
+	}
+
+	ret = mxs_i2c_pio_wait_cplt(i2c);
+	if (ret)
+		return ret;
+
+	/* Clear any dangling IRQs and re-enable interrupts. */
+	writel(MXS_I2C_IRQ_MASK, i2c->regs + MXS_I2C_CTRL1_CLR);
+	writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
+
+	return 0;
+}
+
 /*
  * Low level master read/write transaction.
  */
@@ -316,24 +433,37 @@ static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
 	if (msg->len == 0)
 		return -EINVAL;
 
-	INIT_COMPLETION(i2c->cmd_complete);
-	i2c->cmd_err = 0;
-
-	ret = mxs_i2c_dma_setup_xfer(adap, msg, flags);
-	if (ret)
-		return ret;
+	/*
+	 * The current boundary to select between PIO/DMA transfer method
+	 * is set to 8 bytes, transfers shorter than 8 bytes are transfered
+	 * using PIO mode while longer transfers use DMA. The 8 byte border is
+	 * based on this empirical measurement and a lot of previous frobbing.
+	 */
+	if (msg->len < 8) {
+		ret = mxs_i2c_pio_setup_xfer(adap, msg, flags);
+		if (ret)
+			mxs_i2c_reset(i2c);
+	} else {
+		i2c->cmd_err = 0;
+		INIT_COMPLETION(i2c->cmd_complete);
+		ret = mxs_i2c_dma_setup_xfer(adap, msg, flags);
+		if (ret)
+			return ret;
 
-	ret = wait_for_completion_timeout(&i2c->cmd_complete,
+		ret = wait_for_completion_timeout(&i2c->cmd_complete,
 						msecs_to_jiffies(1000));
-	if (ret == 0)
-		goto timeout;
+		if (ret == 0)
+			goto timeout;
+
+		if (i2c->cmd_err == -ENXIO)
+			mxs_i2c_reset(i2c);
 
-	if (i2c->cmd_err == -ENXIO)
-		mxs_i2c_reset(i2c);
+		ret = i2c->cmd_err;
+	}
 
-	dev_dbg(i2c->dev, "Done with err=%d\n", i2c->cmd_err);
+	dev_dbg(i2c->dev, "Done with err=%d\n", ret);
 
-	return i2c->cmd_err;
+	return ret;
 
 timeout:
 	dev_dbg(i2c->dev, "Timeout!\n");
@@ -403,6 +533,43 @@ static bool mxs_i2c_dma_filter(struct dma_chan *chan, void *param)
 	return true;
 }
 
+static void mxs_i2c_derive_timing(struct mxs_i2c_dev *i2c, int speed)
+{
+	/* The I2C block clock run at 24MHz */
+	const uint32_t clk = 24000000;
+	uint32_t base;
+	uint16_t high_count, low_count, rcv_count, xmit_count;
+	struct device *dev = i2c->dev;
+
+	if (speed > 540000) {
+		dev_warn(dev, "Speed too high (%d Hz), using 540 kHz\n", speed);
+		speed = 540000;
+	} else if (speed < 12000) {
+		dev_warn(dev, "Speed too low (%d Hz), using 12 kHz\n", speed);
+		speed = 12000;
+	}
+
+	/*
+	 * The timing derivation algorithm. There is no documentation for this
+	 * algorithm available, it was derived by using the scope and fiddling
+	 * with constants until the result observed on the scope was good enough
+	 * for 20kHz, 50kHz, 100kHz, 200kHz, 300kHz and 400kHz. It should be
+	 * possible to assume the algorithm works for other frequencies as well.
+	 *
+	 * Note it was necessary to cap the frequency on both ends as it's not
+	 * possible to configure completely arbitrary frequency for the I2C bus
+	 * clock.
+	 */
+	base = ((clk / speed) - 38) / 2;
+	high_count = base + 3;
+	low_count = base - 3;
+	rcv_count = (high_count * 3) / 4;
+	xmit_count = low_count / 4;
+
+	i2c->timing0 = (high_count << 16) | rcv_count;
+	i2c->timing1 = (low_count << 16) | xmit_count;
+}
+
 static int mxs_i2c_get_ofdata(struct mxs_i2c_dev *i2c)
 {
 	uint32_t speed;
@@ -422,12 +589,12 @@ static int mxs_i2c_get_ofdata(struct mxs_i2c_dev *i2c)
 	}
 
 	ret = of_property_read_u32(node, "clock-frequency", &speed);
-	if (ret)
+	if (ret) {
 		dev_warn(dev, "No I2C speed selected, using 100kHz\n");
-	else if (speed == 400000)
-		i2c->speed = &mxs_i2c_400kHz_config;
-	else if (speed != 100000)
-		dev_warn(dev, "Unsupported I2C speed selected, using 100kHz\n");
+		speed = 100000;
+	}
+
+	mxs_i2c_derive_timing(i2c, speed);
 
 	return 0;
 }
@@ -471,7 +638,6 @@ static int mxs_i2c_probe(struct platform_device *pdev)
 		return err;
 
 	i2c->dev = dev;
-	i2c->speed = &mxs_i2c_95kHz_config;
 
 	init_completion(&i2c->cmd_complete);
 
@@ -531,8 +697,6 @@ static int mxs_i2c_remove(struct platform_device *pdev)
 
 	writel(MXS_I2C_CTRL0_SFTRST, i2c->regs + MXS_I2C_CTRL0_SET);
 
-	platform_set_drvdata(pdev, NULL);
-
 	return 0;
 }