void __iomem *reg;
struct i2c_adapter adap;
unsigned long bus_speed;
+ unsigned int clks_per_count;
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;
#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
iic_wr(pd, offs, (iic_rd(pd, offs) | set) & ~clr);
}
-static void activate_ch(struct sh_mobile_i2c_data *pd)
+static u32 sh_mobile_i2c_iccl(unsigned long count_khz, u32 tLOW, u32 tf, int offset)
{
- unsigned long i2c_clk;
- u_int32_t num;
- u_int32_t denom;
- u_int32_t tmp;
-
- /* Wake up device and enable clock */
- pm_runtime_get_sync(pd->dev);
- clk_enable(pd->clk);
-
- /* Get clock rate after clock is enabled */
- i2c_clk = clk_get_rate(pd->clk);
+ /*
+ * 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;
+}
- /* 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.
+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.
*/
- 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);
+ return (((count_khz * (tHIGH + tf)) + 5000) / 10000) + offset;
+}
- /* 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;
+static void sh_mobile_i2c_init(struct sh_mobile_i2c_data *pd)
+{
+ unsigned long i2c_clk_khz;
+ u32 tHIGH, tLOW, tf;
+ int offset;
+
+ /* Get clock rate after clock is enabled */
+ clk_enable(pd->clk);
+ i2c_clk_khz = clk_get_rate(pd->clk) / 1000;
+ i2c_clk_khz /= pd->clks_per_count;
+
+ 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);
+}
+
+static void activate_ch(struct sh_mobile_i2c_data *pd)
+{
+ /* Wake up device and enable clock */
+ pm_runtime_get_sync(pd->dev);
+ clk_enable(pd->clk);
/* Enable channel and configure rx ack */
iic_set_clr(pd, ICCR, ICCR_ICE, 0);
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)
wake_up(&pd->wait);
}
+ /* defeat write posting to avoid spurious WAIT interrupts */
+ iic_rd(pd, ICSR);
+
return IRQ_HANDLED;
}
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;
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;
+ pd->clks_per_count = 1;
+ if (pdata && pdata->clks_per_count)
+ pd->clks_per_count = pdata->clks_per_count;
/* The IIC blocks on SH-Mobile ARM processors
* come with two new bits in ICIC.
if (size > 0x17)
pd->flags |= IIC_FLAG_HAS_ICIC67;
+ sh_mobile_i2c_init(pd);
+
/* Enable Runtime PM for this device.
*
* Also tell the Runtime PM core to ignore children
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;
.runtime_resume = sh_mobile_i2c_runtime_nop,
};
-static const struct of_device_id sh_mobile_i2c_dt_ids[] __devinitconst = {
+static const struct of_device_id sh_mobile_i2c_dt_ids[] = {
{ .compatible = "renesas,rmobile-iic", },
{},
};
projects / firefly-linux-kernel-4.4.55.git / blobdiff