hwmon: (w83795) Fix PWM duty cycle frequency attributes

The PWM duty cycle frequenty attributes are improperly named
(fanN_div instead of pwmN_div) and contain raw values instead of
actual frequencies. Rename them and fix their contents.

Also improve the logic when the user asks for a new frequency, to
always pick the closest supported frequency. The algorithm could
certainly be optimized, but the operation is infrequent enough that
I don't think it's worth the effort.

Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 62 insertions, 28 deletions

diff --git a/drivers/hwmon/w83795.c b/drivers/hwmon/w83795.c
index 458fb297f696..58c61f11ed66 100644
--- a/drivers/hwmon/w83795.c
+++ b/drivers/hwmon/w83795.c
@@ -200,7 +200,6 @@ static const u8 IN_LSB_SHIFT_IDX[][2] = {
 #define W83795_REG_FCMS2                0x208
 #define W83795_REG_TFMR(index)          (0x202 + (index))
 #define W83795_REG_FOMC                 0x20F
-#define W83795_REG_FOPFP(index)         (0x218 + (index))
 
 #define W83795_REG_TSS(index)           (0x209 + (index))
 
@@ -208,18 +207,13 @@ static const u8 IN_LSB_SHIFT_IDX[][2] = {
 #define PWM_START                       1
 #define PWM_NONSTOP                     2
 #define PWM_STOP_TIME                   3
-#define PWM_DIV                         4
+#define PWM_FREQ                        4
 #define W83795_REG_PWM(index, nr) \
         (((nr) == 0 ? 0x210 : \
           (nr) == 1 ? 0x220 : \
           (nr) == 2 ? 0x228 : \
           (nr) == 3 ? 0x230 : 0x218) + (index))
 
-#define W83795_REG_FOPFP_DIV(index) \
-        (((index) < 8) ? ((index) + 1) : \
-         ((index) == 8) ? 12 : \
-         (16 << ((index) - 9)))
-
 #define W83795_REG_FTSH(index)          (0x240 + (index) * 2)
 #define W83795_REG_FTSL(index)          (0x241 + (index) * 2)
 #define W83795_REG_TFTS                 0x250
@@ -304,6 +298,50 @@ static inline s8 temp_to_reg(long val, s8 min, s8 max)
         return SENSORS_LIMIT((val < 0 ? -val : val) / 1000, min, max);
 }
 
+static const u16 pwm_freq_cksel0[16] = {
+        1024, 512, 341, 256, 205, 171, 146, 128,
+        85, 64, 32, 16, 8, 4, 2, 1
+};
+
+static unsigned int pwm_freq_from_reg(u8 reg, u16 clkin)
+{
+        unsigned long base_clock;
+
+        if (reg & 0x80) {
+                base_clock = clkin * 1000 / ((clkin == 48000) ? 384 : 256);
+                return base_clock / ((reg & 0x7f) + 1);
+        } else
+                return pwm_freq_cksel0[reg & 0x0f];
+}
+
+static u8 pwm_freq_to_reg(unsigned long val, u16 clkin)
+{
+        unsigned long base_clock;
+        u8 reg0, reg1;
+        unsigned long best0, best1;
+
+        /* Best fit for cksel = 0 */
+        for (reg0 = 0; reg0 < ARRAY_SIZE(pwm_freq_cksel0) - 1; reg0++) {
+                if (val > (pwm_freq_cksel0[reg0] +
+                           pwm_freq_cksel0[reg0 + 1]) / 2)
+                        break;
+        }
+        if (val < 375)  /* cksel = 1 can't beat this */
+                return reg0;
+        best0 = pwm_freq_cksel0[reg0];
+
+        /* Best fit for cksel = 1 */
+        base_clock = clkin * 1000 / ((clkin == 48000) ? 384 : 256);
+        reg1 = SENSORS_LIMIT(DIV_ROUND_CLOSEST(base_clock, val), 1, 128);
+        best1 = base_clock / reg1;
+        reg1 = 0x80 | (reg1 - 1);
+
+        /* Choose the closest one */
+        if (abs(val - best0) > abs(val - best1))
+                return reg1;
+        else
+                return reg0;
+}
 
 enum chip_types {w83795g, w83795adg};
 
@@ -343,7 +381,8 @@ struct w83795_data {
                                  * no config register, only affected by chip
                                  * type */
         u8 pwm[8][5];           /* Register value, output, start, non stop, stop
-                                 * time, div */
+                                 * time, freq */
+        u16 clkin;              /* CLKIN frequency in kHz */
         u8 pwm_fcms[2];         /* Register value */
         u8 pwm_tfmr[6];         /* Register value */
         u8 pwm_fomc;            /* Register value */
@@ -688,14 +727,14 @@ show_pwm(struct device *dev, struct device_attribute *attr, char *buf)
             to_sensor_dev_attr_2(attr);
         int nr = sensor_attr->nr;
         int index = sensor_attr->index;
-        u16 val;
+        unsigned int val;
 
         switch (nr) {
         case PWM_STOP_TIME:
                 val = time_from_reg(data->pwm[index][nr]);
                 break;
-        case PWM_DIV:
-                val = W83795_REG_FOPFP_DIV(data->pwm[index][nr] & 0x0f);
+        case PWM_FREQ:
+                val = pwm_freq_from_reg(data->pwm[index][nr], data->clkin);
                 break;
         default:
                 val = data->pwm[index][nr];
@@ -716,7 +755,6 @@ store_pwm(struct device *dev, struct device_attribute *attr,
         int nr = sensor_attr->nr;
         int index = sensor_attr->index;
         unsigned long val;
-        int i;
 
         if (strict_strtoul(buf, 10, &val) < 0)
                 return -EINVAL;
@@ -726,28 +764,17 @@ store_pwm(struct device *dev, struct device_attribute *attr,
         case PWM_STOP_TIME:
                 val = time_to_reg(val);
                 break;
-        case PWM_DIV:
-                for (i = 0; i < 16; i++) {
-                        if (W83795_REG_FOPFP_DIV(i) == val) {
-                                val = i;
-                                break;
-                        }
-                }
-                if (i >= 16)
-                        goto err_end;
-                val |= w83795_read(client, W83795_REG_PWM(index, nr)) & 0x80;
+        case PWM_FREQ:
+                val = pwm_freq_to_reg(val, data->clkin);
                 break;
         default:
                 val = SENSORS_LIMIT(val, 0, 0xff);
                 break;
         }
         w83795_write(client, W83795_REG_PWM(index, nr), val);
-        data->pwm[index][nr] = val & 0xff;
+        data->pwm[index][nr] = val;
         mutex_unlock(&data->update_lock);
         return count;
-err_end:
-        mutex_unlock(&data->update_lock);
-        return -EINVAL;
 }
 
 static ssize_t
@@ -1502,8 +1529,8 @@ store_sf_setup(struct device *dev, struct device_attribute *attr,
                 show_pwm, store_pwm, PWM_START, index - 1),             \
         SENSOR_ATTR_2(pwm##index##_stop_time, S_IWUSR | S_IRUGO,        \
                 show_pwm, store_pwm, PWM_STOP_TIME, index - 1),  \
-        SENSOR_ATTR_2(fan##index##_div, S_IWUSR | S_IRUGO,      \
-                show_pwm, store_pwm, PWM_DIV, index - 1),        \
+        SENSOR_ATTR_2(pwm##index##_freq, S_IWUSR | S_IRUGO,     \
+                show_pwm, store_pwm, PWM_FREQ, index - 1),       \
         SENSOR_ATTR_2(pwm##index##_enable, S_IWUSR | S_IRUGO,           \
                 show_pwm_enable, store_pwm_enable, NOT_USED, index - 1), \
         SENSOR_ATTR_2(fan##index##_target, S_IWUSR | S_IRUGO, \
@@ -1685,6 +1712,10 @@ static const struct sensor_device_attribute_2 sda_single_files[] = {
 
 static void w83795_init_client(struct i2c_client *client)
 {
+        struct w83795_data *data = i2c_get_clientdata(client);
+        static const u16 clkin[4] = {   /* in kHz */
+                14318, 24000, 33333, 48000
+        };
         u8 config;
 
         if (reset)
@@ -1697,6 +1728,9 @@ static void w83795_init_client(struct i2c_client *client)
                 w83795_write(client, W83795_REG_CONFIG,
                              config | W83795_REG_CONFIG_START);
         }
+
+        data->clkin = clkin[(config >> 3) & 0x3];
+        dev_dbg(&client->dev, "clkin = %u kHz\n", data->clkin);
 }
 
 static int w83795_get_device_id(struct i2c_client *client)