linux-kernel - [PATCH v1 1/5] pwm: mediatek: add a property "mediatek,num-pwms"

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Date:   Fri, 18 Jan 2019 11:24:41 +0800
From:   Ryder Lee <ryder.lee@...iatek.com>
To:     Thierry Reding <thierry.reding@...il.com>
CC:     Matthias Brugger <matthias.bgg@...il.com>,
        Sean Wang <sean.wang@...nel.org>,
        Weijie Gao <weijie.gao@...iatek.com>,
        <linux-pwm@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        Ryder Lee <ryder.lee@...iatek.com>
Subject: [PATCH v1 1/5] pwm: mediatek: add a property "mediatek,num-pwms"

This adds a property "mediatek,num-pwms" to avoid having an endless
list of compatibles with no differences for the same driver.

Thus, the driver should have backwards compatibility to older DTs.

Signed-off-by: Ryder Lee <ryder.lee@...iatek.com>
---
Changes since v1: add some checks for backwards compatibility.
---
 drivers/pwm/pwm-mediatek.c | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/drivers/pwm/pwm-mediatek.c b/drivers/pwm/pwm-mediatek.c
index eb6674c..81b7e5e 100644
--- a/drivers/pwm/pwm-mediatek.c
+++ b/drivers/pwm/pwm-mediatek.c
@@ -55,7 +55,7 @@ enum {
 };
 
 struct mtk_pwm_platform_data {
-	unsigned int num_pwms;
+	unsigned int num_pwms;	/* it should not be used in the future SoCs */
 	bool pwm45_fixup;
 	bool has_clks;
 };
@@ -226,27 +226,36 @@ static void mtk_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 
 static int mtk_pwm_probe(struct platform_device *pdev)
 {
-	const struct mtk_pwm_platform_data *data;
+	struct device_node *np = pdev->dev.of_node;
 	struct mtk_pwm_chip *pc;
 	struct resource *res;
-	unsigned int i;
+	unsigned int i, num_pwms;
 	int ret;
 
 	pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
 	if (!pc)
 		return -ENOMEM;
 
-	data = of_device_get_match_data(&pdev->dev);
-	if (data == NULL)
-		return -EINVAL;
-	pc->soc = data;
+	pc->soc = of_device_get_match_data(&pdev->dev);
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	pc->regs = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(pc->regs))
 		return PTR_ERR(pc->regs);
 
-	for (i = 0; i < data->num_pwms + 2 && pc->soc->has_clks; i++) {
+	/* Check if we have set 'num-pwms' in DTs. */
+	ret = of_property_read_u32(np, "mediatek,num-pwms", &num_pwms);
+	if (ret < 0) {
+		/* If no, fallback to use SoC data for backwards compatibility. */
+		if (pc->soc->num_pwms) {
+			num_pwms = pc->soc->num_pwms;
+		} else {
+			dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret);
+			return ret;
+		}
+	}
+
+	for (i = 0; i < num_pwms + 2 && pc->soc->has_clks; i++) {
 		pc->clks[i] = devm_clk_get(&pdev->dev, mtk_pwm_clk_name[i]);
 		if (IS_ERR(pc->clks[i])) {
 			dev_err(&pdev->dev, "clock: %s fail: %ld\n",
@@ -260,7 +269,7 @@ static int mtk_pwm_probe(struct platform_device *pdev)
 	pc->chip.dev = &pdev->dev;
 	pc->chip.ops = &mtk_pwm_ops;
 	pc->chip.base = -1;
-	pc->chip.npwm = data->num_pwms;
+	pc->chip.npwm = num_pwms;
 
 	ret = pwmchip_add(&pc->chip);
 	if (ret < 0) {
-- 
1.9.1