diff options
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/busses/i2c-sh_mobile.c | 126 |
1 files changed, 77 insertions, 49 deletions
diff --git a/drivers/i2c/busses/i2c-sh_mobile.c b/drivers/i2c/busses/i2c-sh_mobile.c index 309d0d59289..4dc0cc3611c 100644 --- a/drivers/i2c/busses/i2c-sh_mobile.c +++ b/drivers/i2c/busses/i2c-sh_mobile.c @@ -122,9 +122,9 @@ struct sh_mobile_i2c_data { unsigned long bus_speed; struct clk *clk; u_int8_t icic; - u_int8_t iccl; - u_int8_t icch; u_int8_t flags; + u_int16_t iccl; + u_int16_t icch; spinlock_t lock; wait_queue_head_t wait; @@ -135,7 +135,8 @@ struct sh_mobile_i2c_data { #define IIC_FLAG_HAS_ICIC67 (1 << 0) -#define NORMAL_SPEED 100000 /* FAST_SPEED 400000 */ +#define STANDARD_MODE 100000 +#define FAST_MODE 400000 /* Register offsets */ #define ICDR 0x00 @@ -187,55 +188,81 @@ static void iic_set_clr(struct sh_mobile_i2c_data *pd, int offs, iic_wr(pd, offs, (iic_rd(pd, offs) | set) & ~clr); } +static u32 sh_mobile_i2c_iccl(unsigned long count_khz, u32 tLOW, u32 tf, int offset) +{ + /* + * Conditional expression: + * ICCL >= COUNT_CLK * (tLOW + tf) + * + * SH-Mobile IIC hardware starts counting the LOW period of + * the SCL signal (tLOW) as soon as it pulls the SCL line. + * In order to meet the tLOW timing spec, we need to take into + * account the fall time of SCL signal (tf). Default tf value + * should be 0.3 us, for safety. + */ + return (((count_khz * (tLOW + tf)) + 5000) / 10000) + offset; +} + +static u32 sh_mobile_i2c_icch(unsigned long count_khz, u32 tHIGH, u32 tf, int offset) +{ + /* + * Conditional expression: + * ICCH >= COUNT_CLK * (tHIGH + tf) + * + * SH-Mobile IIC hardware is aware of SCL transition period 'tr', + * and can ignore it. SH-Mobile IIC controller starts counting + * the HIGH period of the SCL signal (tHIGH) after the SCL input + * voltage increases at VIH. + * + * Afterward it turned out calculating ICCH using only tHIGH spec + * will result in violation of the tHD;STA timing spec. We need + * to take into account the fall time of SDA signal (tf) at START + * condition, in order to meet both tHIGH and tHD;STA specs. + */ + return (((count_khz * (tHIGH + tf)) + 5000) / 10000) + offset; +} + static void sh_mobile_i2c_init(struct sh_mobile_i2c_data *pd) { - unsigned long i2c_clk; - u_int32_t num; - u_int32_t denom; - u_int32_t tmp; + unsigned long i2c_clk_khz; + u32 tHIGH, tLOW, tf; + int offset; /* Get clock rate after clock is enabled */ clk_enable(pd->clk); - i2c_clk = clk_get_rate(pd->clk); - - /* Calculate the value for iccl. From the data sheet: - * iccl = (p clock / transfer rate) * (L / (L + H)) - * where L and H are the SCL low/high ratio (5/4 in this case). - * We also round off the result. - */ - num = i2c_clk * 5; - denom = pd->bus_speed * 9; - tmp = num * 10 / denom; - if (tmp % 10 >= 5) - pd->iccl = (u_int8_t)((num/denom) + 1); - else - pd->iccl = (u_int8_t)(num/denom); - - /* one more bit of ICCL in ICIC */ - if (pd->flags & IIC_FLAG_HAS_ICIC67) { - if ((num/denom) > 0xff) - pd->icic |= ICIC_ICCLB8; - else - pd->icic &= ~ICIC_ICCLB8; + i2c_clk_khz = clk_get_rate(pd->clk) / 1000; + + if (pd->bus_speed == STANDARD_MODE) { + tLOW = 47; /* tLOW = 4.7 us */ + tHIGH = 40; /* tHD;STA = tHIGH = 4.0 us */ + tf = 3; /* tf = 0.3 us */ + offset = 0; /* No offset */ + } else if (pd->bus_speed == FAST_MODE) { + tLOW = 13; /* tLOW = 1.3 us */ + tHIGH = 6; /* tHD;STA = tHIGH = 0.6 us */ + tf = 3; /* tf = 0.3 us */ + offset = 0; /* No offset */ + } else { + dev_err(pd->dev, "unrecognized bus speed %lu Hz\n", + pd->bus_speed); + goto out; } - /* Calculate the value for icch. From the data sheet: - icch = (p clock / transfer rate) * (H / (L + H)) */ - num = i2c_clk * 4; - tmp = num * 10 / denom; - if (tmp % 10 >= 5) - pd->icch = (u_int8_t)((num/denom) + 1); + pd->iccl = sh_mobile_i2c_iccl(i2c_clk_khz, tLOW, tf, offset); + /* one more bit of ICCL in ICIC */ + if ((pd->iccl > 0xff) && (pd->flags & IIC_FLAG_HAS_ICIC67)) + pd->icic |= ICIC_ICCLB8; else - pd->icch = (u_int8_t)(num/denom); + pd->icic &= ~ICIC_ICCLB8; + pd->icch = sh_mobile_i2c_icch(i2c_clk_khz, tHIGH, tf, offset); /* one more bit of ICCH in ICIC */ - if (pd->flags & IIC_FLAG_HAS_ICIC67) { - if ((num/denom) > 0xff) - pd->icic |= ICIC_ICCHB8; - else - pd->icic &= ~ICIC_ICCHB8; - } + if ((pd->icch > 0xff) && (pd->flags & IIC_FLAG_HAS_ICIC67)) + pd->icic |= ICIC_ICCHB8; + else + pd->icic &= ~ICIC_ICCHB8; +out: clk_disable(pd->clk); } @@ -252,8 +279,8 @@ static void activate_ch(struct sh_mobile_i2c_data *pd) iic_wr(pd, ICIC, 0); /* Set the clock */ - iic_wr(pd, ICCL, pd->iccl); - iic_wr(pd, ICCH, pd->icch); + iic_wr(pd, ICCL, pd->iccl & 0xff); + iic_wr(pd, ICCH, pd->icch & 0xff); } static void deactivate_ch(struct sh_mobile_i2c_data *pd) @@ -457,8 +484,8 @@ static int start_ch(struct sh_mobile_i2c_data *pd, struct i2c_msg *usr_msg) iic_set_clr(pd, ICCR, ICCR_ICE, 0); /* Set the clock */ - iic_wr(pd, ICCL, pd->iccl); - iic_wr(pd, ICCH, pd->icch); + iic_wr(pd, ICCL, pd->iccl & 0xff); + iic_wr(pd, ICCH, pd->icch & 0xff); pd->msg = usr_msg; pd->pos = -1; @@ -627,8 +654,8 @@ static int sh_mobile_i2c_probe(struct platform_device *dev) goto err_irq; } - /* Use platformd data bus speed or NORMAL_SPEED */ - pd->bus_speed = NORMAL_SPEED; + /* Use platform data bus speed or STANDARD_MODE */ + pd->bus_speed = STANDARD_MODE; if (pdata && pdata->bus_speed) pd->bus_speed = pdata->bus_speed; @@ -675,8 +702,9 @@ static int sh_mobile_i2c_probe(struct platform_device *dev) goto err_all; } - dev_info(&dev->dev, "I2C adapter %d with bus speed %lu Hz\n", - adap->nr, pd->bus_speed); + dev_info(&dev->dev, + "I2C adapter %d with bus speed %lu Hz (L/H=%x/%x)\n", + adap->nr, pd->bus_speed, pd->iccl, pd->icch); of_i2c_register_devices(adap); return 0; |