i2c: fix i2c clock-frequency inaccurate in fast-mode

PD#165568: i2c: fix i2c clock-frequency in fast-mode

1.When i2c controller used in U-boot,may affect i2c
  controller in Kernel,should clear i2c registers.
2.Add i2c default clock-frequency for axg.
3.Add i2c clock-frequency debug sysfs, for i2c-0:
  /sys/class/i2c-adapter/i2c-0/device/speed
4.change clock high/low = 1:2 to 2:3

Change-Id: I44ca7ecd8e2e7aec978f3240ff837121ae478ba7
Signed-off-by: Jian Hu <jian.hu@amlogic.com>

diff --git a/arch/arm64/boot/dts/amlogic/mesonaxg.dtsi b/arch/arm64/boot/dts/amlogic/mesonaxg.dtsi
index 51157cf..4a53384 100644 (file)
--- a/arch/arm64/boot/dts/amlogic/mesonaxg.dtsi
+++ b/arch/arm64/boot/dts/amlogic/mesonaxg.dtsi
@@ -349,6 +349,7 @@
                                #size-cells = <0>;
                                clocks = <&clkc CLKID_I2C>;
                                clock-names = "clk_i2c";
+                               clock-frequency = <100000>;
                        };
 
                        /*i2c-B*/
@@ -362,6 +363,7 @@
                                #size-cells = <0>;
                                clocks = <&clkc CLKID_I2C>;
                                clock-names = "clk_i2c";
+                               clock-frequency = <100000>;
                        };
 
                        /*i2c-C*/
@@ -375,6 +377,7 @@
                                #size-cells = <0>;
                                clocks = <&clkc CLKID_I2C>;
                                clock-names = "clk_i2c";
+                               clock-frequency = <100000>;
                        };
 
                        /*i2c-D*/
@@ -388,6 +391,7 @@
                                #size-cells = <0>;
                                clocks = <&clkc CLKID_I2C>;
                                clock-names = "clk_i2c";
+                               clock-frequency = <100000>;
                        };
                }; /* end of cbus */
 
@@ -417,6 +421,7 @@
                                #size-cells = <0>;
                                clocks = <&clkc CLKID_I2C>;
                                clock-names = "clk_i2c";
+                               clock-frequency = <100000>;
                        };
                };/* end of aobus */
 

diff --git a/drivers/amlogic/i2c/i2c-meson-master.c b/drivers/amlogic/i2c/i2c-meson-master.c
index d9addf0..9210272 100644 (file)
--- a/drivers/amlogic/i2c/i2c-meson-master.c
+++ b/drivers/amlogic/i2c/i2c-meson-master.c
@@ -46,6 +46,7 @@
 #define REG_CTRL_CLKDIV_MASK           GENMASK(21, 12)
 #define REG_CTRL_CLKDIVEXT_SHIFT       28
 #define REG_CTRL_CLKDIVEXT_MASK                GENMASK(29, 28)
+#define REG_FULL_MASK                          GENMASK(31, 0)
 
 #define I2C_TIMEOUT_MS                         500
 #define DEFAULT_FREQ                           100000
@@ -169,7 +170,6 @@ static void meson_i2c_set_clk_div_std(struct meson_i2c *i2c)
        unsigned int div_h, div_l;
        unsigned int div_temp;
 
-
        div_temp = DIV_ROUND_UP(clk_rate, i2c->frequency);
        div_h = DIV_ROUND_UP(div_temp, 2) - i2c->data->delay_ajust;
        div_l = DIV_ROUND_UP(div_temp, 4);
@@ -195,7 +195,7 @@ static void meson_i2c_set_clk_div_std(struct meson_i2c *i2c)
 
        /* set SCL low delay */
        meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, GENMASK(27, 16),
-               (div_l << 16 ) & GENMASK(27, 16));
+               (div_l << 16) & GENMASK(27, 16));
 
        /* enable to control SCL low time */
        meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, BIT(28), BIT(28));
@@ -207,36 +207,48 @@ static void meson_i2c_set_clk_div_std(struct meson_i2c *i2c)
 /*
  * According to I2C-BUS Spec 2.1, in FAST-MODE, LOW period should be at
  * least 1.3uS, and HIGH period should be at lease 0.6. HIGH to LOW
- * ratio as 1 to 2 is more safe.
- * Duty  = H/(H + L) = 1/3     -- duty 33%   H/L = 1/2
+ * ratio as 2 to 5 is more safe.
+ * Duty  = H/(H + L) = 2/5     -- duty 40%%   H/L = 2/3
  * Fast Mode : 400k
  * High Mode : 3400k
  */
 static void meson_i2c_set_clk_div_fast(struct meson_i2c *i2c)
 {
        unsigned long clk_rate = clk_get_rate(i2c->clk);
-       unsigned int div;
+       unsigned int div_h, div_l;
        unsigned int div_temp;
 
+       div_temp = DIV_ROUND_UP(clk_rate * 2, i2c->frequency * 5);
+       div_h = div_temp - i2c->data->delay_ajust;
+       div_l = DIV_ROUND_UP(clk_rate * 3, i2c->frequency * 10);
 
-       div_temp = DIV_ROUND_UP(clk_rate, i2c->frequency) -
-        i2c->data->delay_ajust;
-       div = DIV_ROUND_UP(div_temp, i2c->data->div_factor);
        /* clock divider has 12 bits */
-       if (div >= (1 << 12)) {
+       if (div_h >= (1 << 12)) {
+               dev_err(i2c->dev, "requested bus frequency too low\n");
+               div_h = (1 << 12) - 1;
+       }
+
+       if (div_l >= (1 << 12)) {
                dev_err(i2c->dev, "requested bus frequency too low\n");
-               div = (1 << 12) - 1;
+               div_l = (1 << 12) - 1;
        }
 
        /*control reg:12-21 bits*/
        meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIV_MASK,
-                          (div & GENMASK(9, 0)) << REG_CTRL_CLKDIV_SHIFT);
-
+                          (div_h & GENMASK(9, 0)) << REG_CTRL_CLKDIV_SHIFT);
        meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIVEXT_MASK,
-                          (div >> 10) << REG_CTRL_CLKDIVEXT_SHIFT);
+                          (div_h >> 10) << REG_CTRL_CLKDIVEXT_SHIFT);
+
+
+       /* set SCL low delay */
+       meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, GENMASK(27, 16),
+               (div_l << 16) & GENMASK(27, 16));
+
+       /* enable to control SCL low time */
+       meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, BIT(28), BIT(28));
 
-       dev_dbg(i2c->dev, "%s: clk %lu, freq %u, div %u\n", __func__,
-               clk_rate, i2c->frequency, div);
+       dev_dbg(i2c->dev, "%s: clk %lu, freq %u, div_h %u, div_l %u\n",
+               __func__, clk_rate, i2c->frequency, div_h, div_l);
 }
 
 static void meson_i2c_set_clk_div(struct meson_i2c *i2c)
@@ -492,12 +504,45 @@ static const struct i2c_algorithm meson_i2c_algorithm = {
        .functionality  = meson_i2c_func,
 };
 
+static ssize_t meson_i2c_speed_show(struct device *child,
+                              struct device_attribute *attr, char *buf)
+{
+       struct meson_i2c *i2c =
+               (struct meson_i2c *)dev_get_drvdata(child);
+       return sprintf(buf, "%d\n", i2c->frequency);
+}
+
+static ssize_t meson_i2c_speed_store(struct device *child,
+                                 struct device_attribute *attr,
+                                 const char *buf, size_t size)
+{
+       struct meson_i2c *i2c =
+               (struct meson_i2c *)dev_get_drvdata(child);
+       int ret, val;
+
+       ret = kstrtouint(buf, 0, &val);
+       if (ret)
+               return ret;
+       i2c->frequency = val;
+
+       return ret ? : size;
+}
+
+static DEVICE_ATTR(speed, 0644, meson_i2c_speed_show,
+                                               meson_i2c_speed_store);
+
+int meson_i2c_speed_debug(struct device *dev)
+{
+       return sysfs_create_file(&dev->kobj, &dev_attr_speed.attr);
+}
+
 static int meson_i2c_probe(struct platform_device *pdev)
 {
        struct device_node *np = pdev->dev.of_node;
        struct meson_i2c *i2c;
        struct resource *mem;
        int ret = 0;
+       int i;
 
        i2c = devm_kzalloc(&pdev->dev, sizeof(struct meson_i2c), GFP_KERNEL);
        if (!i2c)
@@ -558,11 +603,21 @@ static int meson_i2c_probe(struct platform_device *pdev)
        i2c->adap.algo_data = i2c;
 
        /*
+        * When the i2c controller has been used in U-boot, it may affect
+        * kernel i2c driver
+        */
+       for (i = 0; i < 8; i++)
+               meson_i2c_set_mask(i2c, REG_CTRL + 4*i, REG_FULL_MASK, 0);
+       /*
         * A transfer is triggered when START bit changes from 0 to 1.
         * Ensure that the bit is set to 0 after probe
         */
        meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
 
+       ret = meson_i2c_speed_debug(&pdev->dev);
+       if (ret)
+               dev_err(&pdev->dev, "Creat speed debug sysfs failed\n");
+
        ret = i2c_add_adapter(&i2c->adap);
        if (ret < 0) {
                clk_unprepare(i2c->clk);