pwm: sti: Take the opportunity to conduct a little house keeping

This includes fixing some Coding Style issues and re-ordering and/or
simplifying a little code.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
[thierry.reding@gmail.com: applied some bikeshedding>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

1 files changed, 81 insertions, 72 deletions

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index 9a1ca1986c30..dd82dc840af9 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -1,8 +1,10 @@
 /*
- * PWM device driver for ST SoCs.
- * Author: Ajit Pal Singh <ajitpal.singh@st.com>
+ * PWM device driver for ST SoCs
+ *
+ * Copyright (C) 2013-2016 STMicroelectronics (R&D) Limited
  *
- * Copyright (C) 2013-2014 STMicroelectronics (R&D) Limited
+ * Author: Ajit Pal Singh <ajitpal.singh@st.com>
+ *         Lee Jones <lee.jones@linaro.org>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -31,14 +33,14 @@
 #define STI_PWM_CTRL            0x50    /* Control/Config register */
 #define STI_INT_EN              0x54    /* Interrupt Enable/Disable register */
 #define STI_INT_STA             0x58    /* Interrupt Status register */
-#define PWM_INT_ACK                     0x5c
-#define PWM_PRESCALE_LOW_MASK           0x0f
-#define PWM_PRESCALE_HIGH_MASK          0xf0
-#define PWM_CPT_EDGE_MASK               0x03
-#define PWM_INT_ACK_MASK                0x1ff
+#define PWM_INT_ACK             0x5c
+#define PWM_PRESCALE_LOW_MASK   0x0f
+#define PWM_PRESCALE_HIGH_MASK  0xf0
+#define PWM_CPT_EDGE_MASK       0x03
+#define PWM_INT_ACK_MASK        0x1ff
 
-#define STI_MAX_CPT_DEVS                4
-#define CPT_DC_MAX                      0xff
+#define STI_MAX_CPT_DEVS        4
+#define CPT_DC_MAX              0xff
 
 /* Regfield IDs */
 enum {
@@ -57,8 +59,9 @@ enum {
         MAX_REGFIELDS
 };
 
-/* Each capture input can be programmed to detect rising-edge, falling-edge,
- * either edge or neither egde
+/*
+ * Each capture input can be programmed to detect rising-edge, falling-edge,
+ * either edge or neither egde.
  */
 enum sti_cpt_edge {
         CPT_EDGE_DISABLED,
@@ -103,13 +106,13 @@ struct sti_pwm_chip {
 };
 
 static const struct reg_field sti_pwm_regfields[MAX_REGFIELDS] = {
-        [PWMCLK_PRESCALE_LOW]   = REG_FIELD(STI_PWM_CTRL, 0, 3),
-        [PWMCLK_PRESCALE_HIGH]  = REG_FIELD(STI_PWM_CTRL, 11, 14),
-        [CPTCLK_PRESCALE]       = REG_FIELD(STI_PWM_CTRL, 4, 8),
-        [PWM_OUT_EN]            = REG_FIELD(STI_PWM_CTRL, 9, 9),
-        [PWM_CPT_EN]            = REG_FIELD(STI_PWM_CTRL, 10, 10),
-        [PWM_CPT_INT_EN]        = REG_FIELD(STI_INT_EN, 1, 4),
-        [PWM_CPT_INT_STAT]      = REG_FIELD(STI_INT_STA, 1, 4),
+        [PWMCLK_PRESCALE_LOW] = REG_FIELD(STI_PWM_CTRL, 0, 3),
+        [PWMCLK_PRESCALE_HIGH] = REG_FIELD(STI_PWM_CTRL, 11, 14),
+        [CPTCLK_PRESCALE] = REG_FIELD(STI_PWM_CTRL, 4, 8),
+        [PWM_OUT_EN] = REG_FIELD(STI_PWM_CTRL, 9, 9),
+        [PWM_CPT_EN] = REG_FIELD(STI_PWM_CTRL, 10, 10),
+        [PWM_CPT_INT_EN] = REG_FIELD(STI_INT_EN, 1, 4),
+        [PWM_CPT_INT_STAT] = REG_FIELD(STI_INT_STA, 1, 4),
 };
 
 static inline struct sti_pwm_chip *to_sti_pwmchip(struct pwm_chip *chip)
@@ -125,7 +128,7 @@ static int sti_pwm_get_prescale(struct sti_pwm_chip *pc, unsigned long period,
 {
         struct sti_pwm_compat_data *cdata = pc->cdata;
         unsigned long clk_rate;
-        unsigned long val;
+        unsigned long value;
         unsigned int ps;
 
         clk_rate = clk_get_rate(pc->pwm_clk);
@@ -135,56 +138,56 @@ static int sti_pwm_get_prescale(struct sti_pwm_chip *pc, unsigned long period,
         }
 
         /*
-         * prescale = ((period_ns * clk_rate) / (10^9 * (max_pwm_count + 1)) - 1
+         * prescale = ((period_ns * clk_rate) / (10^9 * (max_pwm_cnt + 1)) - 1
          */
-        val = NSEC_PER_SEC / clk_rate;
-        val *= cdata->max_pwm_cnt + 1;
+        value = NSEC_PER_SEC / clk_rate;
+        value *= cdata->max_pwm_cnt + 1;
 
-        if (period % val) {
+        if (period % value)
                 return -EINVAL;
-        } else {
-                ps  = period / val - 1;
-                if (ps > cdata->max_prescale)
-                        return -EINVAL;
-        }
+
+        ps  = period / value - 1;
+        if (ps > cdata->max_prescale)
+                return -EINVAL;
+
         *prescale = ps;
 
         return 0;
 }
 
 /*
- * For STiH4xx PWM IP, the PWM period is fixed to 256 local clock cycles.
- * The only way to change the period (apart from changing the PWM input clock)
- * is to change the PWM clock prescaler.
- * The prescaler is of 8 bits, so 256 prescaler values and hence
- * 256 possible period values are supported (for a particular clock rate).
- * The requested period will be applied only if it matches one of these
- * 256 values.
+ * For STiH4xx PWM IP, the PWM period is fixed to 256 local clock cycles. The
+ * only way to change the period (apart from changing the PWM input clock) is
+ * to change the PWM clock prescaler.
+ *
+ * The prescaler is of 8 bits, so 256 prescaler values and hence 256 possible
+ * period values are supported (for a particular clock rate). The requested
+ * period will be applied only if it matches one of these 256 values.
  */
 static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
-                         int duty_ns, int period_ns)
+                          int duty_ns, int period_ns)
 {
         struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
         struct sti_pwm_compat_data *cdata = pc->cdata;
+        unsigned int ncfg, value, prescale = 0;
         struct pwm_device *cur = pc->cur;
         struct device *dev = pc->dev;
-        unsigned int prescale = 0, pwmvalx;
-        int ret;
-        unsigned int ncfg;
         bool period_same = false;
+        int ret;
 
         ncfg = hweight_long(pc->configured);
         if (ncfg)
                 period_same = (period_ns == pwm_get_period(cur));
 
-        /* Allow configuration changes if one of the
-         * following conditions satisfy.
+        /*
+         * Allow configuration changes if one of the following conditions
+         * satisfy.
          * 1. No devices have been configured.
-         * 2. Only one device has been configured and the new request
-         *    is for the same device.
-         * 3. Only one device has been configured and the new request is
-         *    for a new device and period of the new device is same as
-         *    the current configured period.
+         * 2. Only one device has been configured and the new request is for
+         *    the same device.
+         * 3. Only one device has been configured and the new request is for
+         *    a new device and period of the new device is same as the current
+         *    configured period.
          * 4. More than one devices are configured and period of the new
          *    requestis the same as the current period.
          */
@@ -206,15 +209,15 @@ static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
                         if (ret)
                                 goto clk_dis;
 
-                        ret =
-                        regmap_field_write(pc->prescale_low,
-                                           prescale & PWM_PRESCALE_LOW_MASK);
+                        value = prescale & PWM_PRESCALE_LOW_MASK;
+
+                        ret = regmap_field_write(pc->prescale_low, value);
                         if (ret)
                                 goto clk_dis;
 
-                        ret =
-                        regmap_field_write(pc->prescale_high,
-                                (prescale & PWM_PRESCALE_HIGH_MASK) >> 4);
+                        value = (prescale & PWM_PRESCALE_HIGH_MASK) >> 4;
+
+                        ret = regmap_field_write(pc->prescale_high, value);
                         if (ret)
                                 goto clk_dis;
                 }
@@ -225,10 +228,9 @@ static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
                  * PWM pulse = (max_pwm_count + 1) local cycles,
                  * that is continuous pulse: signal never goes low.
                  */
-                pwmvalx = cdata->max_pwm_cnt * duty_ns / period_ns;
+                value = cdata->max_pwm_cnt * duty_ns / period_ns;
 
-                ret = regmap_write(pc->regmap,
-                                   PWM_OUT_VAL(pwm->hwpwm), pwmvalx);
+                ret = regmap_write(pc->regmap, PWM_OUT_VAL(pwm->hwpwm), value);
                 if (ret)
                         goto clk_dis;
 
@@ -237,8 +239,8 @@ static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
                 set_bit(pwm->hwpwm, &pc->configured);
                 pc->cur = pwm;
 
-                dev_dbg(dev, "prescale:%u, period:%i, duty:%i, pwmvalx:%u\n",
-                        prescale, period_ns, duty_ns, pwmvalx);
+                dev_dbg(dev, "prescale:%u, period:%i, duty:%i, value:%u\n",
+                        prescale, period_ns, duty_ns, value);
         } else {
                 return -EINVAL;
         }
@@ -256,10 +258,11 @@ static int sti_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
         int ret = 0;
 
         /*
-         * Since we have a common enable for all PWM devices,
-         * do not enable if already enabled.
+         * Since we have a common enable for all PWM devices, do not enable if
+         * already enabled.
          */
         mutex_lock(&pc->sti_pwm_lock);
+
         if (!pc->en_count) {
                 ret = clk_enable(pc->pwm_clk);
                 if (ret)
@@ -271,12 +274,14 @@ static int sti_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 
                 ret = regmap_field_write(pc->pwm_out_en, 1);
                 if (ret) {
-                        dev_err(dev, "failed to enable PWM device:%d\n",
-                                pwm->hwpwm);
+                        dev_err(dev, "failed to enable PWM device %u: %d\n",
+                                pwm->hwpwm, ret);
                         goto out;
                 }
         }
+
         pc->en_count++;
+
 out:
         mutex_unlock(&pc->sti_pwm_lock);
         return ret;
@@ -287,14 +292,17 @@ static void sti_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
         struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
 
         mutex_lock(&pc->sti_pwm_lock);
+
         if (--pc->en_count) {
                 mutex_unlock(&pc->sti_pwm_lock);
                 return;
         }
+
         regmap_field_write(pc->pwm_out_en, 0);
 
         clk_disable(pc->pwm_clk);
         clk_disable(pc->cpt_clk);
+
         mutex_unlock(&pc->sti_pwm_lock);
 }
 
@@ -422,14 +430,13 @@ static irqreturn_t sti_pwm_interrupt(int irq, void *data)
                  * __|       |_________________|       |________
                  *   ^0      ^1                ^2
                  *
-                 * Capture start by the first available rising edge
-                 * When a capture event occurs, capture value (CPT_VALx)
-                 * is stored, index incremented, capture edge changed.
-                 *
-                 * After the capture, if the index > 1, we have collected
-                 * the necessary data so we signal the thread waiting for it
-                 * and disable the capture by setting capture edge to none
+                 * Capture start by the first available rising edge. When a
+                 * capture event occurs, capture value (CPT_VALx) is stored,
+                 * index incremented, capture edge changed.
                  *
+                 * After the capture, if the index > 1, we have collected the
+                 * necessary data so we signal the thread waiting for it and
+                 * disable the capture by setting capture edge to none
                  */
 
                 regmap_read(pc->regmap,
@@ -445,12 +452,14 @@ static irqreturn_t sti_pwm_interrupt(int irq, void *data)
 
                         ddata->index++;
                         break;
+
                 case 2:
                         regmap_write(pc->regmap,
                                      PWM_CPT_EDGE(devicenum),
                                      CPT_EDGE_DISABLED);
                         wake_up(&ddata->wait);
                         break;
+
                 default:
                         dev_err(dev, "Internal error\n");
                 }
@@ -512,7 +521,7 @@ static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
                 return PTR_ERR(pc->pwm_cpt_en);
 
         pc->pwm_cpt_int_en = devm_regmap_field_alloc(dev, pc->regmap,
-                                                 reg_fields[PWM_CPT_INT_EN]);
+                                                reg_fields[PWM_CPT_INT_EN]);
         if (IS_ERR(pc->pwm_cpt_int_en))
                 return PTR_ERR(pc->pwm_cpt_int_en);
 
@@ -575,9 +584,9 @@ static int sti_pwm_probe(struct platform_device *pdev)
          * Setup PWM data with default values: some values could be replaced
          * with specific ones provided from Device Tree.
          */
-        cdata->reg_fields   = &sti_pwm_regfields[0];
+        cdata->reg_fields = sti_pwm_regfields;
         cdata->max_prescale = 0xff;
-        cdata->max_pwm_cnt  = 255;
+        cdata->max_pwm_cnt = 255;
         cdata->pwm_num_devs = 0;
         cdata->cpt_num_devs = 0;