Merge branch 'for-rafael' of https://git.kernel.org/pub/scm/linux/kernel/git/mzx...

[firefly-linux-kernel-4.4.55.git] / drivers / pwm / pwm-pca9685.c

diff --git a/drivers/pwm/pwm-pca9685.c b/drivers/pwm/pwm-pca9685.c
index 34b5c275a92a3ca592c5fee09b8ca45634caea49..70448a6079b02ede68edf1b2242a5e7b049fb207 100644 (file)
--- a/drivers/pwm/pwm-pca9685.c
+++ b/drivers/pwm/pwm-pca9685.c
@@ -2,6 +2,7 @@
  * Driver for PCA9685 16-channel 12-bit PWM LED controller
  *
  * Copyright (C) 2013 Steffen Trumtrar <s.trumtrar@pengutronix.de>
+ * Copyright (C) 2015 Clemens Gruber <clemens.gruber@pqgruber.com>
  *
  * based on the pwm-twl-led.c driver
  *
@@ -24,6 +25,15 @@
 #include <linux/pwm.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
+#include <linux/delay.h>
+
+/*
+ * Because the PCA9685 has only one prescaler per chip, changing the period of
+ * one channel affects the period of all 16 PWM outputs!
+ * However, the ratio between each configured duty cycle and the chip-wide
+ * period remains constant, because the OFF time is set in proportion to the
+ * counter range.
+ */
 
 #define PCA9685_MODE1          0x00
 #define PCA9685_MODE2          0x01
@@ -42,10 +52,18 @@
 #define PCA9685_ALL_LED_OFF_H  0xFD
 #define PCA9685_PRESCALE       0xFE
 
+#define PCA9685_PRESCALE_MIN   0x03    /* => max. frequency of 1526 Hz */
+#define PCA9685_PRESCALE_MAX   0xFF    /* => min. frequency of 24 Hz */
+
+#define PCA9685_COUNTER_RANGE  4096
+#define PCA9685_DEFAULT_PERIOD 5000000 /* Default period_ns = 1/200 Hz */
+#define PCA9685_OSC_CLOCK_MHZ  25      /* Internal oscillator with 25 MHz */
+
 #define PCA9685_NUMREGS                0xFF
 #define PCA9685_MAXCHAN                0x10
 
 #define LED_FULL               (1 << 4)
+#define MODE1_RESTART          (1 << 7)
 #define MODE1_SLEEP            (1 << 4)
 #define MODE2_INVRT            (1 << 4)
 #define MODE2_OUTDRV           (1 << 2)
@@ -59,6 +77,8 @@ struct pca9685 {
        struct pwm_chip chip;
        struct regmap *regmap;
        int active_cnt;
+       int duty_ns;
+       int period_ns;
 };
 
 static inline struct pca9685 *to_pca(struct pwm_chip *chip)
@@ -72,6 +92,47 @@ static int pca9685_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
        struct pca9685 *pca = to_pca(chip);
        unsigned long long duty;
        unsigned int reg;
+       int prescale;
+
+       if (period_ns != pca->period_ns) {
+               prescale = DIV_ROUND_CLOSEST(PCA9685_OSC_CLOCK_MHZ * period_ns,
+                                            PCA9685_COUNTER_RANGE * 1000) - 1;
+
+               if (prescale >= PCA9685_PRESCALE_MIN &&
+                       prescale <= PCA9685_PRESCALE_MAX) {
+                       /* Put chip into sleep mode */
+                       regmap_update_bits(pca->regmap, PCA9685_MODE1,
+                                          MODE1_SLEEP, MODE1_SLEEP);
+
+                       /* Change the chip-wide output frequency */
+                       regmap_write(pca->regmap, PCA9685_PRESCALE, prescale);
+
+                       /* Wake the chip up */
+                       regmap_update_bits(pca->regmap, PCA9685_MODE1,
+                                          MODE1_SLEEP, 0x0);
+
+                       /* Wait 500us for the oscillator to be back up */
+                       udelay(500);
+
+                       pca->period_ns = period_ns;
+
+                       /*
+                        * If the duty cycle did not change, restart PWM with
+                        * the same duty cycle to period ratio and return.
+                        */
+                       if (duty_ns == pca->duty_ns) {
+                               regmap_update_bits(pca->regmap, PCA9685_MODE1,
+                                                  MODE1_RESTART, 0x1);
+                               return 0;
+                       }
+               } else {
+                       dev_err(chip->dev,
+                               "prescaler not set: period out of bounds!\n");
+                       return -EINVAL;
+               }
+       }
+
+       pca->duty_ns = duty_ns;
 
        if (duty_ns < 1) {
                if (pwm->hwpwm >= PCA9685_MAXCHAN)
@@ -85,6 +146,22 @@ static int pca9685_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
        }
 
        if (duty_ns == period_ns) {
+               /* Clear both OFF registers */
+               if (pwm->hwpwm >= PCA9685_MAXCHAN)
+                       reg = PCA9685_ALL_LED_OFF_L;
+               else
+                       reg = LED_N_OFF_L(pwm->hwpwm);
+
+               regmap_write(pca->regmap, reg, 0x0);
+
+               if (pwm->hwpwm >= PCA9685_MAXCHAN)
+                       reg = PCA9685_ALL_LED_OFF_H;
+               else
+                       reg = LED_N_OFF_H(pwm->hwpwm);
+
+               regmap_write(pca->regmap, reg, 0x0);
+
+               /* Set the full ON bit */
                if (pwm->hwpwm >= PCA9685_MAXCHAN)
                        reg = PCA9685_ALL_LED_ON_H;
                else
@@ -95,7 +172,7 @@ static int pca9685_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
                return 0;
        }
 
-       duty = 4096 * (unsigned long long)duty_ns;
+       duty = PCA9685_COUNTER_RANGE * (unsigned long long)duty_ns;
        duty = DIV_ROUND_UP_ULL(duty, period_ns);
 
        if (pwm->hwpwm >= PCA9685_MAXCHAN)
@@ -112,6 +189,14 @@ static int pca9685_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 
        regmap_write(pca->regmap, reg, ((int)duty >> 8) & 0xf);
 
+       /* Clear the full ON bit, otherwise the set OFF time has no effect */
+       if (pwm->hwpwm >= PCA9685_MAXCHAN)
+               reg = PCA9685_ALL_LED_ON_H;
+       else
+               reg = LED_N_ON_H(pwm->hwpwm);
+
+       regmap_write(pca->regmap, reg, 0);
+
        return 0;
 }
 
@@ -228,6 +313,8 @@ static int pca9685_pwm_probe(struct i2c_client *client,
                        ret);
                return ret;
        }
+       pca->duty_ns = 0;
+       pca->period_ns = PCA9685_DEFAULT_PERIOD;
 
        i2c_set_clientdata(client, pca);
 
@@ -285,7 +372,6 @@ MODULE_DEVICE_TABLE(of, pca9685_dt_ids);
 static struct i2c_driver pca9685_i2c_driver = {
        .driver = {
                .name = "pca9685-pwm",
-               .owner = THIS_MODULE,
                .of_match_table = pca9685_dt_ids,
        },
        .probe = pca9685_pwm_probe,