[U-Boot] [PATCH v3] OMAP: I2C: New read, write and probe functions
Lubomir Popov
lpopov at mm-sol.com
Thu May 30 00:24:42 CEST 2013
Tested on 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 (e.g. unconfigured pads).
- The read/write/probe functions try to identify unconfigured bus.
- Status functions now read irqstatus_raw as per TRM guidelines
(except for OMAP243X and OMAP34XX).
- Driver now supports up to I2C5 (OMAP5).
Signed-off-by: Lubomir Popov <lpopov at mm-sol.com>
---
V3 changes:
- Removed old functions and conditional compilation. New functions
are now built unconditionally for all SoCs using this driver. The
only chip that should break is the OMAP2420 dinosaur.
- Interrupts are enabled for OMAP243X and OMAP34XX only (where we
don't have an irqstatus_raw register).
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 | 482 ++++++++++++++++++++++++++++++---------------
1 file changed, 326 insertions(+), 156 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..deac0ec
--- a/drivers/i2c/omap24xx_i2c.c
+++ b/drivers/i2c/omap24xx_i2c.c
@@ -18,6 +18,18 @@
*
* 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 on 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 (e.g. unconfigured pads).
+ * - 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 +43,11 @@ DECLARE_GLOBAL_DATA_PTR;
#define I2C_TIMEOUT 1000
+/* Absolutely safe for status update at 100 kHz I2C: */
+#define I2C_WAIT 200
+
static int wait_for_bb(void);
-static u16 wait_for_pin(void);
+static u16 wait_for_event(void);
static void flush_fifo(void);
/*
@@ -137,10 +152,14 @@ void i2c_init(int speed, int slaveadd)
/* own address */
writew(slaveadd, &i2c_base->oa);
writew(I2C_CON_EN, &i2c_base->con);
-
- /* have to enable intrrupts or OMAP i2c module doesn't work */
+#if defined(CONFIG_OMAP243X) || defined(CONFIG_OMAP34XX)
+ /*
+ * Have to enable interrupts for OMAP2/3, these IPs don't have
+ * an 'irqstatus_raw' register and we shall have to poll 'stat'
+ */
writew(I2C_IE_XRDY_IE | I2C_IE_RRDY_IE | I2C_IE_ARDY_IE |
I2C_IE_NACK_IE | I2C_IE_AL_IE, &i2c_base->ie);
+#endif
udelay(1000);
flush_fifo();
writew(0xFFFF, &i2c_base->stat);
@@ -150,88 +169,6 @@ void i2c_init(int speed, int slaveadd)
bus_initialized[current_bus] = 1;
}
-static int i2c_read_byte(u8 devaddr, u16 regoffset, u8 alen, u8 *value)
-{
- int i2c_error = 0;
- u16 status;
- int i = 2 - alen;
- u8 tmpbuf[2] = {(regoffset) >> 8, regoffset & 0xff};
- u16 w;
-
- /* wait until bus not busy */
- if (wait_for_bb())
- return 1;
-
- /* one byte only */
- writew(alen, &i2c_base->cnt);
- /* set slave address */
- writew(devaddr, &i2c_base->sa);
- /* no stop bit needed here */
- writew(I2C_CON_EN | I2C_CON_MST | I2C_CON_STT |
- I2C_CON_TRX, &i2c_base->con);
-
- /* send register offset */
- while (1) {
- status = wait_for_pin();
- if (status == 0 || status & I2C_STAT_NACK) {
- i2c_error = 1;
- goto read_exit;
- }
- if (status & I2C_STAT_XRDY) {
- w = tmpbuf[i++];
-#if !(defined(CONFIG_OMAP243X) || defined(CONFIG_OMAP34XX) || \
- defined(CONFIG_OMAP44XX) || defined(CONFIG_AM33XX) || \
- defined(CONFIG_OMAP54XX))
- w |= tmpbuf[i++] << 8;
-#endif
- writew(w, &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(devaddr, &i2c_base->sa);
- /* read one byte from slave */
- writew(1, &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_pin();
- if (status == 0 || status & I2C_STAT_NACK) {
- i2c_error = 1;
- goto read_exit;
- }
- if (status & I2C_STAT_RRDY) {
-#if defined(CONFIG_OMAP243X) || defined(CONFIG_OMAP34XX) || \
- defined(CONFIG_OMAP44XX) || defined(CONFIG_AM33XX) || \
- defined(CONFIG_OMAP54XX)
- *value = readb(&i2c_base->data);
-#else
- *value = readw(&i2c_base->data);
-#endif
- writew(I2C_STAT_RRDY, &i2c_base->stat);
- }
- if (status & I2C_STAT_ARDY) {
- writew(I2C_STAT_ARDY, &i2c_base->stat);
- break;
- }
- }
-
-read_exit:
- flush_fifo();
- writew(0xFFFF, &i2c_base->stat);
- writew(0, &i2c_base->cnt);
- return i2c_error;
-}
-
static void flush_fifo(void)
{ u16 stat;
@@ -241,13 +178,7 @@ static void flush_fifo(void)
while (1) {
stat = readw(&i2c_base->stat);
if (stat == I2C_STAT_RRDY) {
-#if defined(CONFIG_OMAP243X) || defined(CONFIG_OMAP34XX) || \
- defined(CONFIG_OMAP44XX) || defined(CONFIG_AM33XX) || \
- defined(CONFIG_OMAP54XX)
readb(&i2c_base->data);
-#else
- readw(&i2c_base->data);
-#endif
writew(I2C_STAT_RRDY, &i2c_base->stat);
udelay(1000);
} else
@@ -255,6 +186,66 @@ static void flush_fifo(void)
}
}
+#if 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
+/* Old function, uses read access */
int i2c_probe(uchar chip)
{
u16 status;
@@ -275,7 +266,7 @@ 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;
@@ -296,13 +287,7 @@ int i2c_probe(uchar chip)
}
if (status & I2C_STAT_RRDY) {
res = 0;
-#if defined(CONFIG_OMAP243X) || defined(CONFIG_OMAP34XX) || \
- defined(CONFIG_OMAP44XX) || defined(CONFIG_AM33XX) || \
- defined(CONFIG_OMAP54XX)
readb(&i2c_base->data);
-#else
- readw(&i2c_base->data);
-#endif
writew(I2C_STAT_RRDY, &i2c_base->stat);
}
}
@@ -314,10 +299,38 @@ probe_exit:
writew(0xFFFF, &i2c_base->stat);
return res;
}
+#endif /* CONFIG_I2C_PROBE_WRITE */
+/*
+ * 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 i;
+ 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);
@@ -329,25 +342,125 @@ int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
return 1;
}
- for (i = 0; i < len; i++) {
- if (i2c_read_byte(chip, addr + i, alen, &buffer[i])) {
- puts("I2C read: I/O error\n");
- i2c_init(CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);
- 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);
- return 0;
+ /* 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;
}
+/* 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;
- u16 w;
- u8 tmpbuf[2] = {addr >> 8, addr & 0xff};
+ 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;
@@ -355,92 +468,141 @@ int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
if (addr + len > (1 << 16)) {
printf("I2C write: address 0x%x + 0x%x out of range\n",
- addr, len);
+ addr, len);
return 1;
}
- /* wait until bus not busy */
+ /* Wait until bus not busy */
if (wait_for_bb())
return 1;
- /* start address phase - will write regoffset + len bytes data */
- /* TODO consider case when !CONFIG_OMAP243X/34XX/44XX */
+ /* Start address phase - will write regoffset + len bytes data */
writew(alen + len, &i2c_base->cnt);
- /* set slave address */
+ /* Set slave address */
writew(chip, &i2c_base->sa);
- /* stop bit needed here */
+ /* Stop bit needed here */
writew(I2C_CON_EN | I2C_CON_MST | I2C_CON_STT | I2C_CON_TRX |
I2C_CON_STP, &i2c_base->con);
- /* Send address and data */
- for (i = -alen; i < len; i++) {
- status = wait_for_pin();
-
+ 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 error waiting for data ACK (status=0x%x)\n",
- status);
- goto write_exit;
+ printf("i2c_write: error waiting for addr ACK "
+ "(status=0x%x)\n", status);
+ goto wr_exit;
}
-
if (status & I2C_STAT_XRDY) {
- w = (i < 0) ? tmpbuf[2+i] : buffer[i];
-#if !(defined(CONFIG_OMAP243X) || defined(CONFIG_OMAP34XX) || \
- defined(CONFIG_OMAP44XX) || defined(CONFIG_AM33XX) || \
- defined(CONFIG_OMAP54XX))
- w |= ((++i < 0) ? tmpbuf[2+i] : buffer[i]) << 8;
-#endif
- writew(w, &i2c_base->data);
+ alen--;
+ writeb((addr >> (8 * alen)) & 0xff, &i2c_base->data);
writew(I2C_STAT_XRDY, &i2c_base->stat);
- } else {
+ }
+ else {
i2c_error = 1;
- printf("i2c bus not ready for Tx (i=%d)\n", i);
- goto write_exit;
+ 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;
}
}
-write_exit:
+wr_exit:
flush_fifo();
writew(0xFFFF, &i2c_base->stat);
+ writew(0, &i2c_base->cnt);
return i2c_error;
}
+/*
+ * 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_OMAP243X) || defined(CONFIG_OMAP34XX)
while ((stat = readw(&i2c_base->stat) & I2C_STAT_BB) && timeout--) {
+#else
+ /* Read RAW status */
+ while ((stat = readw(&i2c_base->irqstatus_raw) &
+ 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: status=%04x\n",
+ stat);
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_OMAP243X) || defined(CONFIG_OMAP34XX)
status = readw(&i2c_base->stat);
+#else
+ /* Read RAW status */
+ status = readw(&i2c_base->irqstatus_raw);
+#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: status=%04x\n",
+ status);
+ /*
+ * If status 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;
}
@@ -450,28 +612,36 @@ static u16 wait_for_pin(void)
int i2c_set_bus_num(unsigned int bus)
{
- if ((bus < 0) || (bus >= I2C_BUS_MAX)) {
- printf("Bad bus: %d\n", bus);
+ if (bus >= I2C_BUS_MAX) {
+ printf("Bad bus: %x\n", 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)
+ 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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