New i2c_read, i2c_write and i2c_probe functions, tested on OMAP4 (4430/60/70), OMAP5 (5430) and AM335X (3359); should work on older OMAPs and derivatives as well. The only anticipated exception would be the OMAP2420, which shall require driver modification. - 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, 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@mm-sol.com --- V5 changes: - Replaced some printf() with puts(). - Minor formatting touches, checkpatch-clean. V4 changes: - New i2c_probe is built unconditionally, old code is removed. CONFIG_I2C_PROBE_WRITE is no longer needed. - Added a small delay to work around breakage in AM335X SPL. - Some whitespace and general formatting cleanup. 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 | 490 +++++++++++++++++++++++++++------------------ 1 file changed, 299 insertions(+), 191 deletions(-)

diff --git a/drivers/i2c/omap24xx_i2c.c b/drivers/i2c/omap24xx_i2c.c index 54e9b15..ef38d71 100644 --- a/drivers/i2c/omap24xx_i2c.c +++ b/drivers/i2c/omap24xx_i2c.c @@ -18,6 +18,20 @@ * * Adapted for OMAP2420 I2C, r-woodruff2@ti.com * + * Copyright (c) 2013 Lubomir Popov lpopov@mm-sol.com, MM Solutions + * New i2c_read, i2c_write and i2c_probe functions, tested on OMAP4 + * (4430/60/70), OMAP5 (5430) and AM335X (3359); should work on older + * OMAPs and derivatives as well. The only anticipated exception would + * be the OMAP2420, which shall require driver modification. + * - 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, 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). */

#include <common.h> @@ -31,8 +45,11 @@ 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 +154,14 @@ 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); + I2C_IE_NACK_IE | I2C_IE_AL_IE, &i2c_base->ie); +#endif udelay(1000); flush_fifo(); writew(0xFFFF, &i2c_base->stat); @@ -150,88 +171,6 @@ 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 +180,7 @@ 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 +188,10 @@ static void flush_fifo(void) } }

+/* + * 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; @@ -263,61 +200,81 @@ int i2c_probe(uchar chip) if (chip == readw(&i2c_base->oa)) return res;

- /* wait until bus not busy */ + /* Wait until bus is free */ if (wait_for_bb()) return res;

- /* try to read one byte */ - writew(1, &i2c_base->cnt); - /* set slave address */ + /* 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_STP, &i2c_base->con); - - while (1) { - status = wait_for_pin(); - if (status == 0 || status & I2C_STAT_AL) { - res = 1; - goto probe_exit; - } - if (status & I2C_STAT_NACK) { - res = 1; - writew(0xff, &i2c_base->stat); - writew (readw (&i2c_base->con) | I2C_CON_STP, &i2c_base->con); - - if (wait_for_bb()) - res = 1; - - break; - } - if (status & I2C_STAT_ARDY) { - writew(I2C_STAT_ARDY, &i2c_base->stat); - break; - } - 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); - } + /* 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; }

-probe_exit: + /* Check for ACK (!NAK) */ + if (!(status & I2C_STAT_NACK)) { + res = 0; /* Device found */ + udelay(I2C_WAIT); /* Required by AM335X in SPL */ + /* 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(); - /* don't allow any more data in... we don't want it. */ - writew(0, &i2c_base->cnt); writew(0xFFFF, &i2c_base->stat); + writew(0, &i2c_base->cnt); return res; }

+/* + * 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) { + puts("I2C read: addr len < 0\n"); + return 1; + } + if (len < 0) { + puts("I2C read: data len < 0\n"); + return 1; + } + if (buffer == NULL) { + puts("I2C read: NULL pointer passed\n"); + return 1; + }

if (alen > 2) { printf("I2C read: addr len %d not supported\n", alen); @@ -329,24 +286,122 @@ 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) { + puts("I2C write: addr len < 0\n"); + return 1; + } + + if (len < 0) { + puts("I2C write: data len < 0\n"); + return 1; + } + + if (buffer == NULL) { + puts("I2C write: NULL pointer passed\n"); + return 1; + }

if (alen > 2) { printf("I2C write: addr len %d not supported\n", alen); @@ -355,92 +410,137 @@ 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(); - + 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 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 { + 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 bus not ready for Tx (i=%d)\n", i); - goto write_exit; + 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 +550,36 @@ 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) + 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; - else + 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;