[U-Boot] [PATCH v2] OMAP4/5: I2C: New read, write and probe functions

Lubomir Popov lpopov at mm-sol.com
Fri May 24 18:34:11 CEST 2013


Tested and built for OMAP4/5 only, but should work on older OMAPs
and derivatives as well.

- Rewritten i2c_read to operate correctly with all types of chips
  (old function could not read consistent data from some I2C slaves).
- Optimised i2c_write.
- New i2c_probe, optionally selectable via CONFIG_I2C_PROBE_WRITE,
  performs write access vs read. The old probe could hang the system
  under certain conditions.
- The read/write/probe functions try to identify unconfigured bus.
- Status functions now read irqstatus_raw as per TRM guidelines.
- Driver now supports up to I2C5 (OMAP5).

Signed-off-by: Lubomir Popov <lpopov at mm-sol.com>
---
V2 changes:
- Probe tries to identify misconfigured pads as well.
- Status is retrieved from irqstatus_raw rather than from stat.
- Some minor style & format changes.

 drivers/i2c/omap24xx_i2c.c | 414 ++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 387 insertions(+), 27 deletions(-)
 mode change 100644 => 100755 drivers/i2c/omap24xx_i2c.c

diff --git a/drivers/i2c/omap24xx_i2c.c b/drivers/i2c/omap24xx_i2c.c
old mode 100644
new mode 100755
index 54e9b15..4294701
--- a/drivers/i2c/omap24xx_i2c.c
+++ b/drivers/i2c/omap24xx_i2c.c
@@ -18,6 +18,19 @@
  *
  * Adapted for OMAP2420 I2C, r-woodruff2 at ti.com
  *
+ * Copyright (c) 2013 Lubomir Popov <lpopov at mm-sol.com>, MM Solutions
+ * New i2c_read, i2c_write and i2c_probe functions, tested and built
+ * for OMAP4/5 only, but should work on older OMAPs and derivatives
+ * as well.
+ * - Rewritten i2c_read to operate correctly with all types of chips
+ *   (old function could not read consistent data from some I2C slaves).
+ * - Optimized i2c_write.
+ * - New i2c_probe, optionally selectable via CONFIG_I2C_PROBE_WRITE,
+ *   performs write access vs read. The old probe could hang the system
+ *   under certain conditions.
+ * - The read/write/probe functions try to identify unconfigured bus.
+ * - Status functions now read irqstatus_raw as per TRM guidelines.
+ * - Driver now supports up to I2C5 (OMAP5).
  */

 #include <common.h>
@@ -31,8 +44,15 @@ DECLARE_GLOBAL_DATA_PTR;

 #define I2C_TIMEOUT	1000

+#if defined(CONFIG_OMAP44XX) || defined(CONFIG_OMAP54XX)
+/* Absolutely safe for status update at 100 kHz I2C: */
+#define I2C_WAIT	200
+#else
+#define I2C_WAIT	1000
+#endif
+
 static int wait_for_bb(void);
-static u16 wait_for_pin(void);
+static u16 wait_for_event(void);
 static void flush_fifo(void);

 /*
@@ -150,6 +170,7 @@ void i2c_init(int speed, int slaveadd)
 		bus_initialized[current_bus] = 1;
 }

+#if !(defined(CONFIG_OMAP44XX) || defined(CONFIG_OMAP54XX))
 static int i2c_read_byte(u8 devaddr, u16 regoffset, u8 alen, u8 *value)
 {
 	int i2c_error = 0;
@@ -172,7 +193,7 @@ static int i2c_read_byte(u8 devaddr, u16 regoffset, u8 alen, u8 *value)

 	/* send register offset */
 	while (1) {
-		status = wait_for_pin();
+		status = wait_for_event();
 		if (status == 0 || status & I2C_STAT_NACK) {
 			i2c_error = 1;
 			goto read_exit;
@@ -204,7 +225,7 @@ static int i2c_read_byte(u8 devaddr, u16 regoffset, u8 alen, u8 *value)

 	/* receive data */
 	while (1) {
-		status = wait_for_pin();
+		status = wait_for_event();
 		if (status == 0 || status & I2C_STAT_NACK) {
 			i2c_error = 1;
 			goto read_exit;
@@ -231,6 +252,7 @@ read_exit:
 	writew(0, &i2c_base->cnt);
 	return i2c_error;
 }
+#endif

 static void flush_fifo(void)
 {	u16 stat;
@@ -255,6 +277,65 @@ static void flush_fifo(void)
 	}
 }

+#if (defined(CONFIG_OMAP44XX) || defined(CONFIG_OMAP54XX)) && \
+	defined(CONFIG_I2C_PROBE_WRITE)
+/*
+ * i2c_probe: Use write access. Allows to identify addresses that are
+ *            write-only (like the config register of dual-port EEPROMs)
+ */
+int i2c_probe(uchar chip)
+{
+	u16 status;
+	int res = 1; /* default = fail */
+
+	if (chip == readw(&i2c_base->oa))
+		return res;
+
+	/* Wait until bus is free */
+	if (wait_for_bb())
+		return res;
+
+	/* No data transfer, slave addr only */
+	writew(0, &i2c_base->cnt);
+	/* set slave address */
+	writew(chip, &i2c_base->sa);
+	/* stop bit needed here */
+	writew(I2C_CON_EN | I2C_CON_MST | I2C_CON_STT | I2C_CON_TRX |
+	       I2C_CON_STP, &i2c_base->con);
+
+	status = wait_for_event();
+
+	if ((status & ~I2C_STAT_XRDY) == 0 || (status & I2C_STAT_AL)) {
+		/*
+		 * With current high-level command implementation, notifying
+		 * the user shall flood the console with 127 messages. If
+		 * silent exit is desired upon unconfigured bus, remove the
+		 * following 'if' section:
+		 */
+		if (status == I2C_STAT_XRDY)
+			printf("i2c_probe: pads on bus %d "
+                               "probably not configured (status=0x%x)\n",
+			      		current_bus, status);
+
+		goto pr_exit;
+	}
+
+	/* check for ACK (!NAK) */
+	if (!(status & I2C_STAT_NACK)) {
+		res = 0;			/* Device found */
+		/* abort transfer (force idle state) */
+		writew(I2C_CON_MST | I2C_CON_TRX, &i2c_base->con); /* Reset */
+		udelay(1000);
+		writew(I2C_CON_EN | I2C_CON_MST | I2C_CON_TRX |
+			I2C_CON_STP, &i2c_base->con);		/* STP */
+	}
+pr_exit:
+	flush_fifo();
+	writew(0xFFFF, &i2c_base->stat);
+	writew(0, &i2c_base->cnt);
+	return res;
+}
+#else
 int i2c_probe(uchar chip)
 {
 	u16 status;
@@ -275,7 +356,7 @@ int i2c_probe(uchar chip)
 	writew (I2C_CON_EN | I2C_CON_MST | I2C_CON_STT | I2C_CON_STP, &i2c_base->con);

 	while (1) {
-		status = wait_for_pin();
+		status = wait_for_event();
 		if (status == 0 || status & I2C_STAT_AL) {
 			res = 1;
 			goto probe_exit;
@@ -314,7 +395,147 @@ probe_exit:
 	writew(0xFFFF, &i2c_base->stat);
 	return res;
 }
+#endif

+#if defined(CONFIG_OMAP44XX) || defined(CONFIG_OMAP54XX)
+/*
+ * i2c_read: Function now uses a single I2C read transaction with bulk transfer
+ *           of the requested number of bytes (note that the 'i2c md' command
+ *           limits this to 16 bytes anyway). If CONFIG_I2C_REPEATED_START is
+ *           defined in the board config header, this transaction shall be with
+ *           Repeated Start (Sr) between the address and data phases; otherwise
+ *           Stop-Start (P-S) shall be used (some I2C chips do require a P-S).
+ *           The address (reg offset) may be 0, 1 or 2 bytes long.
+ *           Function now reads correctly from chips that return more than one
+ *           byte of data per addressed register (like TI temperature sensors),
+ *           or that do not need a register address at all (such as some clock
+ *           distributors).
+ */
+int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
+{
+	int i2c_error = 0;
+	u16 status;
+
+	if (alen < 0) {
+		printf("I2C read: addr len < 0\n");
+		return 1;
+	}
+	if (len < 0) {
+		printf("I2C read: data len < 0\n");
+		return 1;
+	}
+	if (buffer == NULL) {
+		printf("I2C read: NULL pointer passed\n");
+		return 1;
+	}
+
+	if (alen > 2) {
+		printf("I2C read: addr len %d not supported\n", alen);
+		return 1;
+	}
+
+	if (addr + len > (1 << 16)) {
+		puts("I2C read: address out of range\n");
+		return 1;
+	}
+
+	/* Wait until bus not busy */
+	if (wait_for_bb())
+		return 1;
+
+	/* Zero, one or two bytes reg address (offset) */
+	writew(alen, &i2c_base->cnt);
+	/* Set slave address */
+	writew(chip, &i2c_base->sa);
+
+	if (alen) {
+		/* Must write reg offset first */
+#ifdef CONFIG_I2C_REPEATED_START
+		/* No stop bit, use Repeated Start (Sr) */
+		writew(I2C_CON_EN | I2C_CON_MST | I2C_CON_STT |
+	      		I2C_CON_TRX, &i2c_base->con);
+#else
+		/* Stop - Start (P-S) */
+		writew(I2C_CON_EN | I2C_CON_MST | I2C_CON_STT | I2C_CON_STP |
+	      		I2C_CON_TRX, &i2c_base->con);
+#endif
+		/* Send register offset */
+		while (1) {
+			status = wait_for_event();
+			/* Try to identify bus that is not padconf'd for I2C */
+			if (status == I2C_STAT_XRDY) {
+				i2c_error = 2;
+				printf("i2c_read (addr phase): pads on bus %d "
+                                       "probably not configured (status=0x%x)\n",
+			      		current_bus, status);
+				goto rd_exit;
+			}
+			if (status == 0 || status & I2C_STAT_NACK) {
+				i2c_error = 1;
+				printf("i2c_read: error waiting for addr ACK "
+                                       "(status=0x%x)\n", status);
+				goto rd_exit;
+			}
+			if (alen) {
+				if (status & I2C_STAT_XRDY) {
+					alen--;
+					/* Do we have to use byte access? */
+					writeb((addr >> (8 * alen)) & 0xff,
+                                               &i2c_base->data);
+					writew(I2C_STAT_XRDY, &i2c_base->stat);
+				}
+			}
+			if (status & I2C_STAT_ARDY) {
+				writew(I2C_STAT_ARDY, &i2c_base->stat);
+				break;
+			}
+		}
+	}
+	/* Set slave address */
+	writew(chip, &i2c_base->sa);
+	/* Read len bytes from slave */
+	writew(len, &i2c_base->cnt);
+	/* Need stop bit here */
+	writew(I2C_CON_EN | I2C_CON_MST |
+		I2C_CON_STT | I2C_CON_STP,
+		&i2c_base->con);
+
+	/* Receive data */
+	while (1) {
+		status = wait_for_event();
+		/*
+		 * Try to identify bus that is not padconf'd for I2C. This
+		 * state could be left over from previous transactions if
+		 * the address phase is skipped due to alen=0.
+		 */
+		if (status == I2C_STAT_XRDY) {
+			i2c_error = 2;
+			printf("i2c_read (data phase): pads on bus %d "
+                               "probably not configured (status=0x%x)\n",
+		      		current_bus, status);
+			goto rd_exit;
+		}
+		if (status == 0 || status & I2C_STAT_NACK) {
+			i2c_error = 1;
+			goto rd_exit;
+		}
+		if (status & I2C_STAT_RRDY) {
+			*buffer++ = readb(&i2c_base->data);
+			writew(I2C_STAT_RRDY, &i2c_base->stat);
+		}
+		if (status & I2C_STAT_ARDY) {
+			writew(I2C_STAT_ARDY, &i2c_base->stat);
+			break;
+		}
+	}
+
+rd_exit:
+	flush_fifo();
+	writew(0xFFFF, &i2c_base->stat);
+	writew(0, &i2c_base->cnt);
+	return i2c_error;
+}
+#else
 int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
 {
 	int i;
@@ -339,7 +560,111 @@ int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)

 	return 0;
 }
+#endif

+#if defined(CONFIG_OMAP44XX) || defined(CONFIG_OMAP54XX)
+/* i2c_write: Address (reg offset) may be 0, 1 or 2 bytes long. */
+int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
+{
+	int i;
+	u16 status;
+	int i2c_error = 0;
+
+	if (alen < 0) {
+		printf("I2C write: addr len < 0\n");
+		return 1;
+	}
+
+	if (len < 0) {
+		printf("I2C write: data len < 0\n");
+		return 1;
+	}
+
+	if (buffer == NULL) {
+		printf("I2C write: NULL pointer passed\n");
+		return 1;
+	}
+
+	if (alen > 2) {
+		printf("I2C write: addr len %d not supported\n", alen);
+		return 1;
+	}
+
+	if (addr + len > (1 << 16)) {
+		printf("I2C write: address 0x%x + 0x%x out of range\n",
+                        addr, len);
+		return 1;
+	}
+
+	/* Wait until bus not busy */
+	if (wait_for_bb())
+		return 1;
+
+	/* Start address phase - will write regoffset + len bytes data */
+	writew(alen + len, &i2c_base->cnt);
+	/* Set slave address */
+	writew(chip, &i2c_base->sa);
+	/* Stop bit needed here */
+	writew(I2C_CON_EN | I2C_CON_MST | I2C_CON_STT | I2C_CON_TRX |
+		I2C_CON_STP, &i2c_base->con);
+
+	while (alen) {
+		/* Must write reg offset (one or two bytes) */
+		status = wait_for_event();
+		/* Try to identify bus that is not padconf'd for I2C */
+		if (status == I2C_STAT_XRDY) {
+			i2c_error = 2;
+			printf("i2c_write: pads on bus %d "
+                               "probably not configured (status=0x%x)\n",
+		      		current_bus, status);
+			goto wr_exit;
+		}
+		if (status == 0 || status & I2C_STAT_NACK) {
+			i2c_error = 1;
+			printf("i2c_write: error waiting for addr ACK "
+                               "(status=0x%x)\n", status);
+			goto wr_exit;
+		}
+		if (status & I2C_STAT_XRDY) {
+			alen--;
+			writeb((addr >> (8 * alen)) & 0xff, &i2c_base->data);
+			writew(I2C_STAT_XRDY, &i2c_base->stat);
+		}
+		else {
+			i2c_error = 1;
+			printf("i2c_write: bus not ready for addr Tx "
+                               "(status=0x%x)\n", status);
+			goto wr_exit;
+		}
+	}
+	/* Address phase is over, now write data */
+	for (i = 0; i < len; i++) {
+		status = wait_for_event();
+		if (status == 0 || status & I2C_STAT_NACK) {
+			i2c_error = 1;
+			printf("i2c_write: error waiting for data ACK "
+                               "(status=0x%x)\n", status);
+			goto wr_exit;
+		}
+		if (status & I2C_STAT_XRDY) {
+			writeb(buffer[i], &i2c_base->data);
+			writew(I2C_STAT_XRDY, &i2c_base->stat);
+		}
+		else {
+			i2c_error = 1;
+			printf("i2c_write: bus not ready for data Tx "
+                               "(i=%d)\n", i);
+			goto wr_exit;
+		}
+	}
+
+wr_exit:
+	flush_fifo();
+	writew(0xFFFF, &i2c_base->stat);
+	writew(0, &i2c_base->cnt);
+	return i2c_error;
+}
+#else
 int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
 {
 	int i;
@@ -374,7 +699,7 @@ int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)

 	/* Send address and data */
 	for (i = -alen; i < len; i++) {
-		status = wait_for_pin();
+		status = wait_for_event();

 		if (status == 0 || status & I2C_STAT_NACK) {
 			i2c_error = 1;
@@ -404,43 +729,70 @@ write_exit:
 	writew(0xFFFF, &i2c_base->stat);
 	return i2c_error;
 }
+#endif

+/*
+ * Wait for the bus to be free by checking the Bus Busy (BB)
+ * bit to become clear
+ */
 static int wait_for_bb(void)
 {
 	int timeout = I2C_TIMEOUT;
 	u16 stat;

 	writew(0xFFFF, &i2c_base->stat);	/* clear current interrupts...*/
+#if defined(CONFIG_OMAP44XX) || defined(CONFIG_OMAP54XX)
+	/* Read RAW status */
+	while ((stat = readw(&i2c_base->irqstatus_raw) &
+                I2C_STAT_BB) && timeout--) {
+#else
 	while ((stat = readw(&i2c_base->stat) & I2C_STAT_BB) && timeout--) {
+#endif
 		writew(stat, &i2c_base->stat);
-		udelay(1000);
+		udelay(I2C_WAIT);
 	}

 	if (timeout <= 0) {
-		printf("timed out in wait_for_bb: I2C_STAT=%x\n",
-			readw(&i2c_base->stat));
+		printf("Timed out in wait_for_bb: irqstatus_raw=%04x\n",
+			readw(&i2c_base->irqstatus_raw));
 		return 1;
 	}
 	writew(0xFFFF, &i2c_base->stat);	 /* clear delayed stuff*/
 	return 0;
 }

-static u16 wait_for_pin(void)
+/*
+ * Wait for the I2C controller to complete current action
+ * and update status
+ */
+static u16 wait_for_event(void)
 {
 	u16 status;
 	int timeout = I2C_TIMEOUT;

 	do {
-		udelay(1000);
+		udelay(I2C_WAIT);
+#if defined(CONFIG_OMAP44XX) || defined(CONFIG_OMAP54XX)
+		/* Read RAW status */
+		status = readw(&i2c_base->irqstatus_raw);
+#else
 		status = readw(&i2c_base->stat);
+#endif
 	} while (!(status &
 		   (I2C_STAT_ROVR | I2C_STAT_XUDF | I2C_STAT_XRDY |
 		    I2C_STAT_RRDY | I2C_STAT_ARDY | I2C_STAT_NACK |
 		    I2C_STAT_AL)) && timeout--);

 	if (timeout <= 0) {
-		printf("timed out in wait_for_pin: I2C_STAT=%x\n",
-			readw(&i2c_base->stat));
+		printf("Timed out in wait_for_event: irqstatus_raw=%04x\n",
+			readw(&i2c_base->irqstatus_raw));
+		/*
+		 * If irqstatus_raw is still 0 here, probably the bus pads have
+		 * not been configured for I2C, and/or pull-ups are missing.
+		 */
+		printf("Check if pads/pull-ups of bus %d "
+                       "are properly configured\n",
+			current_bus);
 		writew(0xFFFF, &i2c_base->stat);
 		status = 0;
 	}
@@ -455,23 +807,31 @@ int i2c_set_bus_num(unsigned int bus)
 		return -1;
 	}

-#if I2C_BUS_MAX == 4
-	if (bus == 3)
-		i2c_base = (struct i2c *)I2C_BASE4;
-	else
-	if (bus == 2)
-		i2c_base = (struct i2c *)I2C_BASE3;
-	else
+	switch (bus) {
+		default:
+			bus = 0;	/* Fall through */
+		case 0:
+			i2c_base = (struct i2c *)I2C_BASE1;
+			break;
+		case 1:
+			i2c_base = (struct i2c *)I2C_BASE2;
+			break;
+#if (I2C_BUS_MAX > 2)
+		case 2:
+			i2c_base = (struct i2c *)I2C_BASE3;
+			break;
+#if (I2C_BUS_MAX > 3)
+		case 3:
+			i2c_base = (struct i2c *)I2C_BASE4;
+			break;
+#if (I2C_BUS_MAX > 4) && defined(I2C_BASE5)
+		case 4:
+			i2c_base = (struct i2c *)I2C_BASE5;
+			break;
 #endif
-#if I2C_BUS_MAX == 3
-	if (bus == 2)
-		i2c_base = (struct i2c *)I2C_BASE3;
-	else
 #endif
-	if (bus == 1)
-		i2c_base = (struct i2c *)I2C_BASE2;
-	else
-		i2c_base = (struct i2c *)I2C_BASE1;
+#endif
+	}

 	current_bus = bus;

-- 
1.7.12.4 (Apple Git-37)



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