[U-Boot] [PATCH 07/24] mxc_i2c: combine i2c_imx_bus_busy and i2c_imx_trx_complete into wait_for_sr_state

Troy Kisky
2012-06-22T04:12:02Z

Not using udelay gives a more accurate timeout. The current implementation of udelay
in imx-common does not seem to wait at all for a udelay(1).

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
---
drivers/i2c/mxc_i2c.c | 71 ++++++++++++++++---------------------------------
1 file changed, 23 insertions(+), 48 deletions(-)

diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c
index 4f12b9e..7b1b75c 100644
--- a/drivers/i2c/mxc_i2c.c
+++ b/drivers/i2c/mxc_i2c.c
@@ -63,8 +63,6 @@ struct mxc_i2c_regs {
#error "define CONFIG_SYS_I2C_BASE to use the mxc_i2c driver"
#endif

-#define I2C_MAX_TIMEOUT 10000
-
static u16 i2c_clk_div[50][2] = {
{ 22, 0x20 }, { 24, 0x21 }, { 26, 0x22 }, { 28, 0x23 },
{ 30, 0x00 }, { 32, 0x24 }, { 36, 0x25 }, { 40, 0x26 },
@@ -164,48 +162,25 @@ unsigned int i2c_get_bus_speed(void)
return mxc_get_clock(MXC_IPG_PERCLK) / i2c_clk_div[clk_div][0];
}

-/*
- * Wait for bus to be busy (or free if for_busy = 0)
- *
- * for_busy = 1: Wait for IBB to be asserted
- * for_busy = 0: Wait for IBB to be de-asserted
- */
-int i2c_imx_bus_busy(int for_busy)
-{
- struct mxc_i2c_regs *i2c_regs = (struct mxc_i2c_regs *)I2C_BASE;
- unsigned int temp;
-
- int timeout = I2C_MAX_TIMEOUT;
-
- while (timeout--) {
- temp = readb(&i2c_regs->i2sr);
+#define ST_BUS_IDLE (0 | (I2SR_IBB << 8))
+#define ST_BUS_BUSY (I2SR_IBB | (I2SR_IBB << 8))
+#define ST_IIF (I2SR_IIF | (I2SR_IIF << 8))

- if (for_busy && (temp & I2SR_IBB))
- return 0;
- if (!for_busy && !(temp & I2SR_IBB))
- return 0;
-
- udelay(1);
- }
-
- return 1;
-}
-
-/*
- * Wait for transaction to complete
- */
-int i2c_imx_trx_complete(void)
+static unsigned wait_for_sr_state(struct mxc_i2c_regs *i2c_regs, unsigned state)
{
- struct mxc_i2c_regs *i2c_regs = (struct mxc_i2c_regs *)I2C_BASE;
- int timeout = I2C_MAX_TIMEOUT;
-
- while (timeout--) {
- if (readb(&i2c_regs->i2sr) & I2SR_IIF)
- return 0;
-
- udelay(1);
+ unsigned sr;
+ ulong elapsed;
+ ulong start_time = get_timer(0);
+ for (;;) {
+ sr = readb(&i2c_regs->i2sr);
+ if ((sr & (state >> 8)) == (unsigned char)state)
+ return sr;
+ elapsed = get_timer(start_time);
+ if (elapsed > (CONFIG_SYS_HZ / 10)) /* .1 seconds */
+ break;
}
-
+ printf("%s: failed sr=%x cr=%x state=%x\n", __func__,
+ sr, readb(&i2c_regs->i2cr), state);
return -ETIMEDOUT;
}

@@ -215,7 +190,7 @@ static int tx_byte(struct mxc_i2c_regs *i2c_regs, u8 byte)

writeb(0, &i2c_regs->i2sr);
writeb(byte, &i2c_regs->i2dr);
- ret = i2c_imx_trx_complete();
+ ret = wait_for_sr_state(i2c_regs, ST_IIF);
if (ret < 0)
return ret;
ret = readb(&i2c_regs->i2sr);
@@ -245,8 +220,8 @@ int i2c_imx_start(void)
temp |= I2CR_MSTA;
writeb(temp, &i2c_regs->i2cr);

- result = i2c_imx_bus_busy(1);
- if (result)
+ result = wait_for_sr_state(i2c_regs, ST_BUS_BUSY);
+ if (result < 0)
return result;

temp |= I2CR_MTX | I2CR_TX_NO_AK;
@@ -268,7 +243,7 @@ void i2c_imx_stop(void)
temp &= ~(I2CR_MSTA | I2CR_MTX);
writeb(temp, &i2c_regs->i2cr);

- i2c_imx_bus_busy(0);
+ wait_for_sr_state(i2c_regs, ST_BUS_IDLE);

/* Disable I2C controller */
writeb(0, &i2c_regs->i2cr);
@@ -333,8 +308,8 @@ int i2c_read(uchar chip, uint addr, int alen, uchar *buf, int len)

/* read data */
for (i = 0; i < len; i++) {
- ret = i2c_imx_trx_complete();
- if (ret)
+ ret = wait_for_sr_state(i2c_regs, ST_IIF);
+ if (ret < 0)
return ret;

/*
@@ -345,7 +320,7 @@ int i2c_read(uchar chip, uint addr, int alen, uchar *buf, int len)
temp = readb(&i2c_regs->i2cr);
temp &= ~(I2CR_MSTA | I2CR_MTX);
writeb(temp, &i2c_regs->i2cr);
- i2c_imx_bus_busy(0);
+ wait_for_sr_state(i2c_regs, ST_BUS_IDLE);
} else if (i == (len - 2)) {
temp = readb(&i2c_regs->i2cr);
temp |= I2CR_TX_NO_AK;
--
1.7.9.5