linux-kernel - [PATCH 08/11] pwm: sti: Add support for PWM Capture IRQs

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Message-Id: <1455109348-32767-9-git-send-email-lee.jones@linaro.org>
Date:	Wed, 10 Feb 2016 13:02:25 +0000
From:	Lee Jones <lee.jones@...aro.org>
To:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	thierry.reding@...il.com, linux-pwm@...r.kernel.org,
	ajitpal.singh@...com
Cc:	kernel@...inux.com, maxime.coquelin@...com,
	Lee Jones <lee.jones@...aro.org>
Subject: [PATCH 08/11] pwm: sti: Add support for PWM Capture IRQs

Here we're requesting the PWM Capture IRQ and supplying the
handler which will be called in the event of an IRQ fire to
handle it.

Signed-off-by: Lee Jones <lee.jones@...aro.org>
---
 drivers/pwm/pwm-sti.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 90 insertions(+), 1 deletion(-)

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index fca692a..82a69e4 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -12,6 +12,7 @@
 
 #include <linux/clk.h>
 #include <linux/gpio.h>
+#include <linux/interrupt.h>
 #include <linux/math64.h>
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
@@ -94,7 +95,9 @@ struct sti_pwm_chip {
 	struct regmap_field *prescale_low;
 	struct regmap_field *prescale_high;
 	struct regmap_field *pwm_out_en;
+	struct regmap_field *pwm_cpt_en;
 	struct regmap_field *pwm_cpt_int_en;
+	struct regmap_field *pwm_cpt_int_stat;
 	struct pwm_chip chip;
 	struct pwm_device *cur;
 	unsigned long configured;
@@ -314,6 +317,74 @@ static const struct pwm_ops sti_pwm_ops = {
 	.owner = THIS_MODULE,
 };
 
+static irqreturn_t sti_pwm_interrupt(int irq, void *data)
+{
+	struct sti_pwm_chip *pc = data;
+	struct device *dev = pc->dev;
+	struct sti_cpt_data *d;
+	int channel;
+	int cpt_int_stat;
+	int reg;
+	int ret = IRQ_NONE;
+
+	ret = regmap_field_read(pc->pwm_cpt_int_stat, &cpt_int_stat);
+	if (ret)
+		return ret;
+
+	while (cpt_int_stat) {
+		channel = ffs(cpt_int_stat) - 1;
+
+		d = pc->cpt_data[channel];
+
+		/*
+		 * Capture input:
+		 *    _______                   _______
+		 *   |       |                 |       |
+		 * __|       |_________________|       |________
+		 *   ^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
+		 *
+		 */
+
+		regmap_read(pc->regmap,
+			    PWM_CPT_VAL(channel), &d->snapshot[d->index]);
+
+		switch (d->index) {
+		case 0:
+		case 1:
+			regmap_read(pc->regmap, PWM_CPT_EDGE(channel), &reg);
+			reg ^= PWM_CPT_EDGE_MASK;
+			regmap_write(pc->regmap, PWM_CPT_EDGE(channel), reg);
+
+			d->index++;
+			break;
+		case 2:
+			regmap_write(pc->regmap,
+				     PWM_CPT_EDGE(channel), CPT_EDGE_DISABLED);
+			wake_up(&d->wait);
+			break;
+		default:
+			dev_err(dev, "Internal error\n");
+		}
+
+		clear_bit(channel, (unsigned long int *)&cpt_int_stat);
+
+		ret = IRQ_HANDLED;
+	}
+
+	/* Just ACK everything */
+	regmap_write(pc->regmap, PWM_INT_ACK, PWM_INT_ACK_MASK);
+
+	return ret;
+}
+
 static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
 {
 	struct device *dev = pc->dev;
@@ -354,6 +425,11 @@ static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
 	if (IS_ERR(pc->pwm_cpt_int_en))
 		return PTR_ERR(pc->pwm_cpt_int_en);
 
+	pc->pwm_cpt_int_stat = devm_regmap_field_alloc(dev, pc->regmap,
+						reg_fields[PWM_CPT_INT_STAT]);
+	if (IS_ERR(pc->pwm_cpt_int_stat))
+		return PTR_ERR(pc->pwm_cpt_int_stat);
+
 	return 0;
 }
 
@@ -371,7 +447,7 @@ static int sti_pwm_probe(struct platform_device *pdev)
 	struct sti_pwm_chip *pc;
 	struct resource *res;
 	unsigned int chan;
-	int ret;
+	int ret, irq;
 
 	pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL);
 	if (!pc)
@@ -392,6 +468,19 @@ static int sti_pwm_probe(struct platform_device *pdev)
 	if (IS_ERR(pc->regmap))
 		return PTR_ERR(pc->regmap);
 
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "Failed to obtain IRQ\n");
+		return -ENODEV;
+	}
+
+	ret = devm_request_irq(&pdev->dev, irq, sti_pwm_interrupt,
+			       0, pdev->name, (void *) pc);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to request IRQ\n");
+		return ret;
+	}
+
 	/*
 	 * Setup PWM data with default values: some values could be replaced
 	 * with specific ones provided from Device Tree.
-- 
1.9.1