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(a)gmail.com>
---
drivers/i2c/mxc_i2c.c | 391 +++++++++++++++++++++++++++++++++----------------
1 files changed, 262 insertions(+), 129 deletions(-)
diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c
index 89d1973..449d765 100644
--- a/drivers/i2c/mxc_i2c.c
+++ b/drivers/i2c/mxc_i2c.c
@@ -68,218 +68,351 @@
#endif
#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 }
+};
+
+static u8 clk_idx;
-static inline void i2c_reset(void)
-{
- writew(0, I2C_BASE + I2CR); /* Reset module */
- writew(0, I2C_BASE + I2SR);
- writew(I2CR_IEN, I2C_BASE + I2CR);
-}
-
-void i2c_init(int speed, int unused)
+/*
+ * Calculate and set proper clock divider
+ *
+ * FIXME: remove #ifdefs !
+ */
+static void i2c_imx_set_clk(unsigned int rate)
{
- int freq;
+ unsigned int i2c_clk_rate;
+ unsigned int div;
int i;
+ /* Divider value calculation */
#if defined(CONFIG_MX31)
struct clock_control_regs *sc_regs =
(struct clock_control_regs *)CCM_BASE;
- freq = mx31_get_ipg_clk();
+ i2c_clk_rate = mx31_get_ipg_clk();
/* start the required I2C clock */
writel(readl(&sc_regs->cgr0) | (3 << I2C_CLK_OFFSET),
&sc_regs->cgr0);
#else
- freq = mxc_get_clock(MXC_IPG_PERCLK);
+ i2c_clk_rate = mxc_get_clock(MXC_IPG_CLK);
#endif
+ 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;
+}
- for (i = 0; i < 0x1f; i++)
- if (freq / div[i] <= speed)
- break;
-
- debug("%s: speed: %d\n", __func__, speed);
+/*
+ * Reset I2C Controller
+ */
+void i2c_reset(void)
+{
+ writeb(0, I2C_BASE + I2CR); /* Reset module */
+ writeb(0, I2C_BASE + I2SR);
+}
- writew(i, I2C_BASE + IFDR);
+/*
+ * Init I2C Bus
+ */
+void i2c_init(int speed, int unused)
+{
+ i2c_imx_set_clk(speed);
i2c_reset();
}
-static int wait_idle(void)
+/*
+ * 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)
{
+ 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;
}
-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) {
+ writeb(0, I2C_BASE + I2SR);
+ return 0;
+ }
+
udelay(1);
- writew(0, I2C_BASE + I2SR); /* clear interrupt */
+ }
- return timeout;
+ return 1;
}
-static int wait_complete(void)
+/*
+ * Check if the transaction was ACKed
+ */
+int i2c_imx_acked(void)
{
- int timeout = I2C_MAX_TIMEOUT;
+ return readb(I2C_BASE + I2SR) & I2SR_RX_NO_AK;
+}
- while ((!(readw(I2C_BASE + I2SR) & I2SR_ICF)) && (--timeout)) {
- writew(0, I2C_BASE + I2SR);
- udelay(1);
- }
- udelay(200);
+/*
+ * 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);
- return timeout;
-}
+ /* Enable I2C controller */
+ writeb(0, I2C_BASE + I2SR);
+ writeb(I2CR_IEN, I2C_BASE + I2CR);
+ /* Wait controller to be stable */
+ udelay(50);
-static int tx_byte(u8 byte)
-{
- writew(byte, I2C_BASE + I2DR);
+ /* Start I2C transaction */
+ temp = readb(I2C_BASE + I2CR);
+ temp |= I2CR_MSTA;
+ writeb(temp, I2C_BASE + I2CR);
+
+ result = i2c_imx_bus_busy(1);
+ if (result)
+ return result;
+
+ temp |= I2CR_MTX | I2CR_TX_NO_AK;
+ writeb(temp, I2C_BASE + I2CR);
- if (!wait_complete() || readw(I2C_BASE + I2SR) & I2SR_RX_NO_AK)
- return -1;
return 0;
}
-static int rx_byte(int last)
+/*
+ * Stop the controller
+ */
+void i2c_imx_stop()
{
- if (!wait_complete())
- return -1;
+ unsigned int temp = 0;
- if (last)
- writew(I2CR_IEN, I2C_BASE + I2CR);
+ /* Stop I2C transaction */
+ temp = readb(I2C_BASE + I2CR);
+ temp |= ~(I2CR_MSTA | I2CR_MTX);
+ writeb(temp, I2C_BASE + I2CR);
- return readw(I2C_BASE + I2DR);
+ i2c_imx_bus_busy(0);
+
+ /* Disable I2C controller */
+ writeb(0, I2C_BASE + I2CR);
}
-int i2c_probe(uchar chip)
+/*
+ * Set chip address and access mode
+ *
+ * read = 1: READ access
+ * read = 0: WRITE access
+ */
+int i2c_imx_set_chip_addr(uchar chip, int read)
{
int ret;
- writew(0, I2C_BASE + I2CR); /* Reset module */
- writew(I2CR_IEN, I2C_BASE + I2CR);
+ writeb((chip << 1) | read, I2C_BASE + I2DR);
+
+ ret = i2c_imx_trx_complete();
+ if (ret)
+ return ret;
- writew(I2CR_IEN | I2CR_MSTA | I2CR_MTX, I2C_BASE + I2CR);
- ret = tx_byte(chip << 1);
- writew(I2CR_IEN | I2CR_MTX, I2C_BASE + I2CR);
+ ret = i2c_imx_acked();
+ if (ret)
+ return ret;
return ret;
}
-static int i2c_addr(uchar chip, uint addr, int alen)
+/*
+ * 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;
+
+ for (i = 0; i < (8 * alen); i += 8) {
+ writeb((addr >> i) & 0xff, I2C_BASE + I2DR);
+
+ ret = i2c_imx_trx_complete();
+ if (ret)
break;
- i2c_reset();
- for (i = 0; i < I2C_MAX_TIMEOUT; i++)
- udelay(1);
- }
- if (retry >= I2C_MAX_RETRIES) {
- debug("%s:bus is busy(%x)\n",
- __func__, readw(I2C_BASE + I2SR));
- return -1;
- }
- writew(I2CR_IEN | I2CR_MSTA | I2CR_MTX, I2C_BASE + I2CR);
- if (!wait_busy()) {
- debug("%s:trigger start fail(%x)\n",
- __func__, readw(I2C_BASE + I2SR));
- return -1;
+ ret = i2c_imx_acked();
+ if (ret)
+ break;
}
- if (tx_byte(chip << 1) || (readw(I2C_BASE + I2SR) & I2SR_RX_NO_AK)) {
- debug("%s:chip address cycle fail(%x)\n",
- __func__, readw(I2C_BASE + I2SR));
- return -1;
- }
- while (alen--)
- if (tx_byte((addr >> (alen * 8)) & 0xff) ||
- (readw(I2C_BASE + I2SR) & I2SR_RX_NO_AK)) {
- debug("%s:device address cycle fail(%x)\n",
- __func__, readw(I2C_BASE + I2SR));
- return -1;
- }
- return 0;
+ return ret;
}
-int i2c_read(uchar chip, uint addr, int alen, uchar *buf, int len)
+/*
+ * Try if a chip add given address responds (probe the chip)
+ */
+int i2c_probe(uchar chip)
{
- int timeout = I2C_MAX_TIMEOUT;
int ret;
- debug("%s chip: 0x%02x addr: 0x%04x alen: %d len: %d\n",
- __func__, chip, addr, alen, len);
+ ret = i2c_imx_start();
+ if (ret)
+ return ret;
- if (i2c_addr(chip, addr, alen)) {
- printf("i2c_addr failed\n");
- return -1;
- }
+ ret = i2c_imx_set_chip_addr(chip, 0);
+ if (ret)
+ return ret;
- writew(I2CR_IEN | I2CR_MSTA | I2CR_MTX | I2CR_RSTA, I2C_BASE + I2CR);
+ i2c_imx_stop();
- if (tx_byte(chip << 1 | 1))
- return -1;
+ return ret;
+}
- writew(I2CR_IEN | I2CR_MSTA |
- ((len == 1) ? I2CR_TX_NO_AK : 0),
- I2C_BASE + I2CR);
+/*
+ * Read data from I2C device
+ */
+int i2c_read(uchar chip, uint addr, int alen, uchar *buf, int len)
+{
+ int ret;
+ unsigned int temp;
+ int i;
- ret = readw(I2C_BASE + I2DR);
+ ret = i2c_imx_start();
+ if (ret)
+ return ret;
+
+ /* write slave address */
+ ret = i2c_imx_set_chip_addr(chip, 0);
+ if (ret)
+ return ret;
+
+ ret = i2c_imx_set_reg_addr(addr, alen);
+ if (ret)
+ return ret;
+
+ temp = readb(I2C_BASE + I2CR);
+ temp |= I2CR_RSTA;
+ writeb(temp, I2C_BASE + I2CR);
+
+ ret = i2c_imx_set_chip_addr(chip, 1);
+ if (ret)
+ return ret;
+
+ /* setup bus to read data */
+ temp = readb(I2C_BASE + I2CR);
+ temp &= ~I2CR_MTX;
+ if (len == 1)
+ temp &= ~I2CR_TX_NO_AK;
+ writeb(temp, I2C_BASE + I2CR);
+ readb(I2C_BASE + I2DR);
+
+ /* read data */
+ for (i = 0; i < len; i++) {
+ ret = i2c_imx_trx_complete();
+ if (ret)
+ return ret;
+
+ /*
+ * It must generate STOP before read I2DR to prevent
+ * controller from generating another clock cycle
+ */
+ if (i == (len - 1)) {
+ temp = readb(I2C_BASE + I2CR);
+ temp &= ~(I2CR_MSTA | I2CR_MTX);
+ writeb(temp, I2C_BASE + I2CR);
+ i2c_imx_bus_busy(0);
+ } else if (i == (len - 2)) {
+ temp = readb(I2C_BASE + I2CR);
+ temp |= I2CR_TX_NO_AK;
+ writeb(temp, I2C_BASE + I2CR);
+ }
- while (len--) {
- ret = rx_byte(len == 0);
- if (ret < 0)
- return -1;
- *buf++ = ret;
- if (len <= 1)
- writew(I2CR_IEN | I2CR_MSTA |
- I2CR_TX_NO_AK,
- I2C_BASE + I2CR);
+ buf[i] = readb(I2C_BASE + I2DR);
}
- writew(I2CR_IEN, I2C_BASE + I2CR);
-
- while (readw(I2C_BASE + I2SR) & I2SR_IBB && --timeout)
- udelay(1);
+ i2c_imx_stop();
- return 0;
+ return ret;
}
+/*
+ * Write data to I2C device
+ */
int i2c_write(uchar chip, uint addr, int alen, uchar *buf, int len)
{
- int timeout = I2C_MAX_TIMEOUT;
- debug("%s chip: 0x%02x addr: 0x%04x alen: %d len: %d\n",
- __func__, chip, addr, alen, len);
+ int ret;
+ unsigned int temp;
+ int i;
- if (i2c_addr(chip, addr, alen))
- return -1;
+ ret = i2c_imx_start();
+ if (ret)
+ return ret;
- while (len--)
- if (tx_byte(*buf++))
- return -1;
+ /* write slave address */
+ ret = i2c_imx_set_chip_addr(chip, 0);
+ if (ret)
+ return ret;
- writew(I2CR_IEN, I2C_BASE + I2CR);
+ ret = i2c_imx_set_reg_addr(addr, alen);
+ if (ret)
+ return ret;
- while (readw(I2C_BASE + I2SR) & I2SR_IBB && --timeout)
- udelay(1);
+ for (i = 0; i < len; i++) {
+ writeb(buf[i], I2C_BASE + I2DR);
- return 0;
-}
+ ret = i2c_imx_trx_complete();
+ if (ret)
+ return ret;
+
+ ret = i2c_imx_acked();
+ if (ret)
+ return ret;
+ }
+ i2c_imx_stop();
+
+ return ret;
+}
#endif /* CONFIG_HARD_I2C */
--
1.7.5.3
