diff options
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/mxs_i2c.c | 134 |
1 files changed, 67 insertions, 67 deletions
diff --git a/drivers/i2c/mxs_i2c.c b/drivers/i2c/mxs_i2c.c index 9594008..d3cb727 100644 --- a/drivers/i2c/mxs_i2c.c +++ b/drivers/i2c/mxs_i2c.c @@ -29,9 +29,9 @@ static struct mxs_i2c_regs *mxs_i2c_get_base(struct i2c_adapter *adap) return (struct mxs_i2c_regs *)MXS_I2C0_BASE; } -static unsigned int mxs_i2c_get_bus_speed(void) +static unsigned int mxs_i2c_get_bus_speed(struct i2c_adapter *adap) { - struct mxs_i2c_regs *i2c_regs = mxs_i2c_get_base(NULL); + struct mxs_i2c_regs *i2c_regs = mxs_i2c_get_base(adap); uint32_t clk = mxc_get_clock(MXC_XTAL_CLK); uint32_t timing0; @@ -43,11 +43,52 @@ static unsigned int mxs_i2c_get_bus_speed(void) return clk / ((((timing0 >> 16) - 3) * 2) + 38); } -static void mxs_i2c_reset(void) +static uint mxs_i2c_set_bus_speed(struct i2c_adapter *adap, uint speed) +{ + struct mxs_i2c_regs *i2c_regs = mxs_i2c_get_base(adap); + /* + * The timing derivation algorithm. There is no documentation for this + * algorithm available, it was derived by using the scope and fiddling + * with constants until the result observed on the scope was good enough + * for 20kHz, 50kHz, 100kHz, 200kHz, 300kHz and 400kHz. It should be + * possible to assume the algorithm works for other frequencies as well. + * + * Note it was necessary to cap the frequency on both ends as it's not + * possible to configure completely arbitrary frequency for the I2C bus + * clock. + */ + uint32_t clk = mxc_get_clock(MXC_XTAL_CLK); + uint32_t base = ((clk / speed) - 38) / 2; + uint16_t high_count = base + 3; + uint16_t low_count = base - 3; + uint16_t rcv_count = (high_count * 3) / 4; + uint16_t xmit_count = low_count / 4; + + if (speed > 540000) { + printf("MXS I2C: Speed too high (%d Hz)\n", speed); + return -EINVAL; + } + + if (speed < 12000) { + printf("MXS I2C: Speed too low (%d Hz)\n", speed); + return -EINVAL; + } + + writel((high_count << 16) | rcv_count, &i2c_regs->hw_i2c_timing0); + writel((low_count << 16) | xmit_count, &i2c_regs->hw_i2c_timing1); + + writel((0x0030 << I2C_TIMING2_BUS_FREE_OFFSET) | + (0x0030 << I2C_TIMING2_LEADIN_COUNT_OFFSET), + &i2c_regs->hw_i2c_timing2); + + return 0; +} + +static void mxs_i2c_reset(struct i2c_adapter *adap) { - struct mxs_i2c_regs *i2c_regs = mxs_i2c_get_base(NULL); + struct mxs_i2c_regs *i2c_regs = mxs_i2c_get_base(adap); int ret; - int speed = mxs_i2c_get_bus_speed(); + int speed = mxs_i2c_get_bus_speed(adap); ret = mxs_reset_block(&i2c_regs->hw_i2c_ctrl0_reg); if (ret) { @@ -62,12 +103,12 @@ static void mxs_i2c_reset(void) writel(I2C_QUEUECTRL_PIO_QUEUE_MODE, &i2c_regs->hw_i2c_queuectrl_set); - i2c_set_bus_speed(speed); + mxs_i2c_set_bus_speed(adap, speed); } -static void mxs_i2c_setup_read(uint8_t chip, int len) +static void mxs_i2c_setup_read(struct i2c_adapter *adap, uint8_t chip, int len) { - struct mxs_i2c_regs *i2c_regs = mxs_i2c_get_base(NULL); + struct mxs_i2c_regs *i2c_regs = mxs_i2c_get_base(adap); writel(I2C_QUEUECMD_RETAIN_CLOCK | I2C_QUEUECMD_PRE_SEND_START | I2C_QUEUECMD_MASTER_MODE | I2C_QUEUECMD_DIRECTION | @@ -83,10 +124,10 @@ static void mxs_i2c_setup_read(uint8_t chip, int len) writel(I2C_QUEUECTRL_QUEUE_RUN, &i2c_regs->hw_i2c_queuectrl_set); } -static int mxs_i2c_write(uchar chip, uint addr, int alen, - uchar *buf, int blen, int stop) +static int mxs_i2c_write(struct i2c_adapter *adap, uchar chip, uint addr, + int alen, uchar *buf, int blen, int stop) { - struct mxs_i2c_regs *i2c_regs = mxs_i2c_get_base(NULL); + struct mxs_i2c_regs *i2c_regs = mxs_i2c_get_base(adap); uint32_t data, tmp; int i, remain, off; int timeout = MXS_I2C_MAX_TIMEOUT; @@ -141,9 +182,9 @@ static int mxs_i2c_write(uchar chip, uint addr, int alen, return 0; } -static int mxs_i2c_wait_for_ack(void) +static int mxs_i2c_wait_for_ack(struct i2c_adapter *adap) { - struct mxs_i2c_regs *i2c_regs = mxs_i2c_get_base(NULL); + struct mxs_i2c_regs *i2c_regs = mxs_i2c_get_base(adap); uint32_t tmp; int timeout = MXS_I2C_MAX_TIMEOUT; @@ -175,7 +216,7 @@ static int mxs_i2c_wait_for_ack(void) return 0; err: - mxs_i2c_reset(); + mxs_i2c_reset(adap); return 1; } @@ -183,26 +224,26 @@ static int mxs_i2c_if_read(struct i2c_adapter *adap, uint8_t chip, uint addr, int alen, uint8_t *buffer, int len) { - struct mxs_i2c_regs *i2c_regs = mxs_i2c_get_base(NULL); + struct mxs_i2c_regs *i2c_regs = mxs_i2c_get_base(adap); uint32_t tmp = 0; int timeout = MXS_I2C_MAX_TIMEOUT; int ret; int i; - ret = mxs_i2c_write(chip, addr, alen, NULL, 0, 0); + ret = mxs_i2c_write(adap, chip, addr, alen, NULL, 0, 0); if (ret) { debug("MXS I2C: Failed writing address\n"); return ret; } - ret = mxs_i2c_wait_for_ack(); + ret = mxs_i2c_wait_for_ack(adap); if (ret) { debug("MXS I2C: Failed writing address\n"); return ret; } - mxs_i2c_setup_read(chip, len); - ret = mxs_i2c_wait_for_ack(); + mxs_i2c_setup_read(adap, chip, len); + ret = mxs_i2c_wait_for_ack(adap); if (ret) { debug("MXS I2C: Failed reading address\n"); return ret; @@ -235,13 +276,13 @@ static int mxs_i2c_if_write(struct i2c_adapter *adap, uint8_t chip, int len) { int ret; - ret = mxs_i2c_write(chip, addr, alen, buffer, len, 1); + ret = mxs_i2c_write(adap, chip, addr, alen, buffer, len, 1); if (ret) { debug("MXS I2C: Failed writing address\n"); return ret; } - ret = mxs_i2c_wait_for_ack(); + ret = mxs_i2c_wait_for_ack(adap); if (ret) debug("MXS I2C: Failed writing address\n"); @@ -251,58 +292,17 @@ static int mxs_i2c_if_write(struct i2c_adapter *adap, uint8_t chip, static int mxs_i2c_probe(struct i2c_adapter *adap, uint8_t chip) { int ret; - ret = mxs_i2c_write(chip, 0, 1, NULL, 0, 1); + ret = mxs_i2c_write(adap, chip, 0, 1, NULL, 0, 1); if (!ret) - ret = mxs_i2c_wait_for_ack(); - mxs_i2c_reset(); + ret = mxs_i2c_wait_for_ack(adap); + mxs_i2c_reset(adap); return ret; } -static uint mxs_i2c_set_bus_speed(struct i2c_adapter *adap, uint speed) -{ - struct mxs_i2c_regs *i2c_regs = mxs_i2c_get_base(NULL); - /* - * The timing derivation algorithm. There is no documentation for this - * algorithm available, it was derived by using the scope and fiddling - * with constants until the result observed on the scope was good enough - * for 20kHz, 50kHz, 100kHz, 200kHz, 300kHz and 400kHz. It should be - * possible to assume the algorithm works for other frequencies as well. - * - * Note it was necessary to cap the frequency on both ends as it's not - * possible to configure completely arbitrary frequency for the I2C bus - * clock. - */ - uint32_t clk = mxc_get_clock(MXC_XTAL_CLK); - uint32_t base = ((clk / speed) - 38) / 2; - uint16_t high_count = base + 3; - uint16_t low_count = base - 3; - uint16_t rcv_count = (high_count * 3) / 4; - uint16_t xmit_count = low_count / 4; - - if (speed > 540000) { - printf("MXS I2C: Speed too high (%d Hz)\n", speed); - return -EINVAL; - } - - if (speed < 12000) { - printf("MXS I2C: Speed too low (%d Hz)\n", speed); - return -EINVAL; - } - - writel((high_count << 16) | rcv_count, &i2c_regs->hw_i2c_timing0); - writel((low_count << 16) | xmit_count, &i2c_regs->hw_i2c_timing1); - - writel((0x0030 << I2C_TIMING2_BUS_FREE_OFFSET) | - (0x0030 << I2C_TIMING2_LEADIN_COUNT_OFFSET), - &i2c_regs->hw_i2c_timing2); - - return 0; -} - static void mxs_i2c_init(struct i2c_adapter *adap, int speed, int slaveaddr) { - mxs_i2c_reset(); - i2c_set_bus_speed(speed); + mxs_i2c_reset(adap); + mxs_i2c_set_bus_speed(adap, speed); return; } |