[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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