On 07/13/2011 11:53 AM, Marek Vasut wrote:
Rewrite the mxc_i2c driver.
- This version is much closer to Linux implementation.
- Fixes IPG_PERCLK being incorrectly used as clock source
- Fixes behaviour of the driver on iMX51
- Clean up coding style a bit ;-)
Signed-off-by: Marek Vasut marek.vasut@gmail.com
Hi Marek,
I have added Heiko in CC. He is the Maintainer for I2C.
#define I2C_MAX_TIMEOUT 10000 -#define I2C_MAX_RETRIES 3
-static u16 div[] = { 30, 32, 36, 42, 48, 52, 60, 72, 80, 88, 104, 128, 144,
160, 192, 240, 288, 320, 384, 480, 576, 640, 768, 960,1152, 1280, 1536, 1920, 2304, 2560, 3072, 3840};+static u16 i2c_clk_div[50][2] = {
- { 22, 0x20 }, { 24, 0x21 }, { 26, 0x22 }, { 28, 0x23 },
- { 30, 0x00 }, { 32, 0x24 }, { 36, 0x25 }, { 40, 0x26 },
- { 42, 0x03 }, { 44, 0x27 }, { 48, 0x28 }, { 52, 0x05 },
- { 56, 0x29 }, { 60, 0x06 }, { 64, 0x2A }, { 72, 0x2B },
- { 80, 0x2C }, { 88, 0x09 }, { 96, 0x2D }, { 104, 0x0A },
- { 112, 0x2E }, { 128, 0x2F }, { 144, 0x0C }, { 160, 0x30 },
- { 192, 0x31 }, { 224, 0x32 }, { 240, 0x0F }, { 256, 0x33 },
- { 288, 0x10 }, { 320, 0x34 }, { 384, 0x35 }, { 448, 0x36 },
- { 480, 0x13 }, { 512, 0x37 }, { 576, 0x14 }, { 640, 0x38 },
- { 768, 0x39 }, { 896, 0x3A }, { 960, 0x17 }, { 1024, 0x3B },
- { 1152, 0x18 }, { 1280, 0x3C }, { 1536, 0x3D }, { 1792, 0x3E },
- { 1920, 0x1B }, { 2048, 0x3F }, { 2304, 0x1C }, { 2560, 0x1D },
- { 3072, 0x1E }, { 3840, 0x1F }
+};
You have added an array with fixed values as indicated in the Freescale's manual (Table 26-7 for i.MX31, Table 40-7 for MX51, Table 41-12 for MX53). What about to add also some comments about these changes ?
-void i2c_init(int speed, int unused) +/*
- Calculate and set proper clock divider
- FIXME: remove #ifdefs !
- */
Agree. I have prepared a patch to get rid of this mx31_ specialties. I will post soon. Then we can use mxc_get_clock(MXC_IPG_CLK) for all i.MX processors.
- div = (i2c_clk_rate + rate - 1) / rate;
- if (div < i2c_clk_div[0][0])
i = 0;- else if (div > i2c_clk_div[ARRAY_SIZE(i2c_clk_div) - 1][0])
i = ARRAY_SIZE(i2c_clk_div) - 1;- else
for (i = 0; i2c_clk_div[i][0] < div; i++);- /* Store divider value */
- writeb(div, I2C_BASE + IFDR);
- clk_idx = div;
It seems to me ok - you replaced a computed value, that does not obtain exactly the value indicated in the manual, with the closest value of the table.
+int i2c_imx_bus_busy(int for_busy) {
- unsigned int temp;
- int timeout = I2C_MAX_TIMEOUT;
- while ((readw(I2C_BASE + I2SR) & I2SR_IBB) && --timeout) {
writew(0, I2C_BASE + I2SR);
- while (timeout--) {
temp = readb(I2C_BASE + I2SR);if (for_busy && (temp & I2SR_IBB))return 0;if (!for_busy && !(temp & I2SR_IBB))return 0;- udelay(1); }
- return timeout ? timeout : (!(readw(I2C_BASE + I2SR) & I2SR_IBB));
- return 1;
}
It is not clear to me why you add a way to go out from the function. If it is busy, should we not wait at least until the timeout variable becomes zero ?
-static int wait_busy(void) +/*
- Wait for transaction to complete
- */
+int i2c_imx_trx_complete(void) { int timeout = I2C_MAX_TIMEOUT;
- while (!(readw(I2C_BASE + I2SR) & I2SR_IBB) && --timeout)
- while (timeout--) {
if (readb(I2C_BASE + I2SR) & I2SR_IIF) {
If we wait for completion, should we not check the ICF bit instead of IIF, as done before your patch ?
+/*
- Start the controller
- */
+int i2c_imx_start(void) +{
- unsigned int temp = 0;
- int result;
- writew(0, I2C_BASE + I2SR); /* clear interrupt */
- writeb(clk_idx, I2C_BASE + IFDR);
Well, as you talk about cleaning up the code, what about to replace the direct access to the registers with a C structure, as part of your clean up ?
+/*
- Write register address
- */
+int i2c_imx_set_reg_addr(uint addr, int alen) {
- int i, retry = 0;
- for (retry = 0; retry < 3; retry++) {
if (wait_idle())
- int ret;
- int i;
mmmhh...it seems to me you change completely the logic here. Heiko, waht do you think about ?
Best regards, Stefano Babic