The Exynos5 i2c driver does not handle NACKs properly. This change:
- fixes the NACK processing problem (do not continue transaction if address cycle was NACKed)
- eliminates a fair amount of duplicate code
Signed-off-by: Vadim Bendebury vbendeb@chromium.org Reviewed-by: Simon Glass sjg@google.com Signed-off-by: Naveen Krishna Chatradhi ch.naveen@samsung.com --- Changes since v1: 1. Removed the compilation error mentioned by Heiko for VCMA9 board...
drivers/i2c/s3c24x0_i2c.c | 214 +++++++++++++++++++-------------------------- 1 file changed, 90 insertions(+), 124 deletions(-)
diff --git a/drivers/i2c/s3c24x0_i2c.c b/drivers/i2c/s3c24x0_i2c.c index cd09c78..c65360d 100644 --- a/drivers/i2c/s3c24x0_i2c.c +++ b/drivers/i2c/s3c24x0_i2c.c @@ -43,7 +43,7 @@ #define I2C_START_STOP 0x20 /* START / STOP */ #define I2C_TXRX_ENA 0x10 /* I2C Tx/Rx enable */
-#define I2C_TIMEOUT 1 /* 1 second */ +#define I2C_TIMEOUT_MS 1000 /* 1 second */
/* @@ -84,22 +84,26 @@ static void SetI2CSCL(int x) } #endif
+/* + * Wait til the byte transfer is completed. + * + * @param i2c- pointer to the appropriate i2c register bank. + * @return I2C_OK, if transmission was ACKED + * I2C_NACK, if transmission was NACKED + * I2C_NOK_TIMEOUT, if transaction did not complete in I2C_TIMEOUT_MS + */ + static int WaitForXfer(struct s3c24x0_i2c *i2c) { - int i; + ulong start_time = get_timer(0);
- i = I2C_TIMEOUT * 10000; - while (!(readl(&i2c->iiccon) & I2CCON_IRPND) && (i > 0)) { - udelay(100); - i--; - } + do { + if (readl(&i2c->iiccon) & I2CCON_IRPND) + return (readl(&i2c->iicstat) & I2CSTAT_NACK) ? + I2C_NACK : I2C_OK; + } while (get_timer(start_time) < I2C_TIMEOUT_MS);
- return (readl(&i2c->iiccon) & I2CCON_IRPND) ? I2C_OK : I2C_NOK_TOUT; -} - -static int IsACK(struct s3c24x0_i2c *i2c) -{ - return !(readl(&i2c->iicstat) & I2CSTAT_NACK); + return I2C_NOK_TOUT; }
static void ReadWriteByte(struct s3c24x0_i2c *i2c) @@ -180,21 +184,27 @@ unsigned int i2c_get_bus_num(void)
void i2c_init(int speed, int slaveadd) { + int i; struct s3c24x0_i2c *i2c; #if !(defined CONFIG_EXYNOS4 || defined CONFIG_EXYNOS5) struct s3c24x0_gpio *gpio = s3c24x0_get_base_gpio(); #endif - int i; + ulong start_time = get_timer(0);
/* By default i2c channel 0 is the current bus */ g_current_bus = 0; i2c = get_base_i2c();
- /* wait for some time to give previous transfer a chance to finish */ - i = I2C_TIMEOUT * 1000; - while ((readl(&i2c->iicstat) & I2CSTAT_BSY) && (i > 0)) { - udelay(1000); - i--; + /* + * In case the previous transfer is still going, wait to give it a + * chance to finish. + */ + while (readl(&i2c->iicstat) & I2CSTAT_BSY) { + if (get_timer(start_time) > I2C_TIMEOUT_MS) { + printf("%s: I2C bus busy for %p\n", __func__, + &i2c->iicstat); + return; + } }
#if !(defined CONFIG_EXYNOS4 || defined CONFIG_EXYNOS5) @@ -260,7 +270,8 @@ static int i2c_transfer(struct s3c24x0_i2c *i2c, unsigned char data[], unsigned short data_len) { - int i, result; + int i = 0, result; + ulong start_time = get_timer(0);
if (data == 0 || data_len == 0) { /*Don't support data transfer of no length or to address 0 */ @@ -268,128 +279,78 @@ static int i2c_transfer(struct s3c24x0_i2c *i2c, return I2C_NOK; }
- /* Check I2C bus idle */ - i = I2C_TIMEOUT * 1000; - while ((readl(&i2c->iicstat) & I2CSTAT_BSY) && (i > 0)) { - udelay(1000); - i--; + while (readl(&i2c->iicstat) & I2CSTAT_BSY) { + if (get_timer(start_time) > I2C_TIMEOUT_MS) + return I2C_NOK_TOUT; }
- if (readl(&i2c->iicstat) & I2CSTAT_BSY) - return I2C_NOK_TOUT; - writel(readl(&i2c->iiccon) | I2CCON_ACKGEN, &i2c->iiccon); - result = I2C_OK;
- switch (cmd_type) { - case I2C_WRITE: - if (addr && addr_len) { - writel(chip, &i2c->iicds); - /* send START */ - writel(I2C_MODE_MT | I2C_TXRX_ENA | I2C_START_STOP, - &i2c->iicstat); - i = 0; - while ((i < addr_len) && (result == I2C_OK)) { - result = WaitForXfer(i2c); - writel(addr[i], &i2c->iicds); - ReadWriteByte(i2c); - i++; - } - i = 0; - while ((i < data_len) && (result == I2C_OK)) { - result = WaitForXfer(i2c); - writel(data[i], &i2c->iicds); - ReadWriteByte(i2c); - i++; - } - } else { - writel(chip, &i2c->iicds); - /* send START */ - writel(I2C_MODE_MT | I2C_TXRX_ENA | I2C_START_STOP, - &i2c->iicstat); - i = 0; - while ((i < data_len) && (result == I2C_OK)) { - result = WaitForXfer(i2c); - writel(data[i], &i2c->iicds); - ReadWriteByte(i2c); - i++; - } + /* Get the slave chip address going */ + writel(chip, &i2c->iicds); + if ((cmd_type == I2C_WRITE) || (addr && addr_len)) + writel(I2C_MODE_MT | I2C_TXRX_ENA | I2C_START_STOP, + &i2c->iicstat); + else + writel(I2C_MODE_MR | I2C_TXRX_ENA | I2C_START_STOP, + &i2c->iicstat); + + /* Wait for chip address to transmit. */ + result = WaitForXfer(i2c); + if (result != I2C_OK) + goto bailout; + + /* If register address needs to be transmitted - do it now. */ + if (addr && addr_len) { + while ((i < addr_len) && (result == I2C_OK)) { + writel(addr[i++], &i2c->iicds); + ReadWriteByte(i2c); + result = WaitForXfer(i2c); } + i = 0; + if (result != I2C_OK) + goto bailout; + }
- if (result == I2C_OK) + switch (cmd_type) { + case I2C_WRITE: + while ((i < data_len) && (result == I2C_OK)) { + writel(data[i++], &i2c->iicds); + ReadWriteByte(i2c); result = WaitForXfer(i2c); - - /* send STOP */ - writel(I2C_MODE_MT | I2C_TXRX_ENA, &i2c->iicstat); - ReadWriteByte(i2c); + } break;
case I2C_READ: if (addr && addr_len) { + /* + * Register address has been sent, now send slave chip + * address again to start the actual read transaction. + */ writel(chip, &i2c->iicds); - /* send START */ - writel(I2C_MODE_MT | I2C_TXRX_ENA | I2C_START_STOP, - &i2c->iicstat); - result = WaitForXfer(i2c); - if (IsACK(i2c)) { - i = 0; - while ((i < addr_len) && (result == I2C_OK)) { - writel(addr[i], &i2c->iicds); - ReadWriteByte(i2c); - result = WaitForXfer(i2c); - i++; - } - - writel(chip, &i2c->iicds); - /* resend START */ - writel(I2C_MODE_MR | I2C_TXRX_ENA | - I2C_START_STOP, &i2c->iicstat); - ReadWriteByte(i2c); - result = WaitForXfer(i2c); - i = 0; - while ((i < data_len) && (result == I2C_OK)) { - /* disable ACK for final READ */ - if (i == data_len - 1) - writel(readl(&i2c->iiccon) - & ~I2CCON_ACKGEN, - &i2c->iiccon); - ReadWriteByte(i2c); - result = WaitForXfer(i2c); - data[i] = readl(&i2c->iicds); - i++; - } - } else { - result = I2C_NACK; - } - - } else { - writel(chip, &i2c->iicds); - /* send START */ + + /* Generate a re-START. */ writel(I2C_MODE_MR | I2C_TXRX_ENA | I2C_START_STOP, &i2c->iicstat); + ReadWriteByte(i2c); result = WaitForXfer(i2c);
- if (IsACK(i2c)) { - i = 0; - while ((i < data_len) && (result == I2C_OK)) { - /* disable ACK for final READ */ - if (i == data_len - 1) - writel(readl(&i2c->iiccon) & - ~I2CCON_ACKGEN, - &i2c->iiccon); - ReadWriteByte(i2c); - result = WaitForXfer(i2c); - data[i] = readl(&i2c->iicds); - i++; - } - } else { - result = I2C_NACK; - } + if (result != I2C_OK) + goto bailout; }
- /* send STOP */ - writel(I2C_MODE_MR | I2C_TXRX_ENA, &i2c->iicstat); - ReadWriteByte(i2c); + while ((i < data_len) && (result == I2C_OK)) { + /* disable ACK for final READ */ + if (i == data_len - 1) + writel(readl(&i2c->iiccon) + & ~I2CCON_ACKGEN, + &i2c->iiccon); + ReadWriteByte(i2c); + result = WaitForXfer(i2c); + data[i++] = readl(&i2c->iicds); + } + if (result == I2C_NACK) + result = I2C_OK; /* Normal terminated read. */ break;
default: @@ -398,6 +359,11 @@ static int i2c_transfer(struct s3c24x0_i2c *i2c, break; }
+bailout: + /* Send STOP. */ + writel(I2C_MODE_MR | I2C_TXRX_ENA, &i2c->iicstat); + ReadWriteByte(i2c); + return result; }