linux-kernel - [PATCH 2/4] mmc: pwrseq: sd8787: add support for specifying the delay b/w power and reset

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Message-ID: <20210806113001.821660-3-claudiu.beznea@microchip.com>
Date:   Fri, 6 Aug 2021 14:29:59 +0300
From:   Claudiu Beznea <claudiu.beznea@...rochip.com>
To:     <ulf.hansson@...aro.org>, <robh+dt@...nel.org>,
        <nicolas.ferre@...rochip.com>, <alexandre.belloni@...tlin.com>,
        <ludovic.desroches@...rochip.com>
CC:     <linux-mmc@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        Claudiu Beznea <claudiu.beznea@...rochip.com>
Subject: [PATCH 2/4] mmc: pwrseq: sd8787: add support for specifying the delay b/w power and reset

Add support to be able to specify the delay to be introduced b/w
power and reset lines on power up sequence. With this, the driver
could also be used by other WiFi chips (e.g. WILC1000/WILC3000
devices that need a delay of 5ms b/w power and reset line for
a proper powering up sequence).

Signed-off-by: Claudiu Beznea <claudiu.beznea@...rochip.com>
---
 drivers/mmc/core/pwrseq_sd8787.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/core/pwrseq_sd8787.c b/drivers/mmc/core/pwrseq_sd8787.c
index 68a826f1c0a1..a554eefdf1b1 100644
--- a/drivers/mmc/core/pwrseq_sd8787.c
+++ b/drivers/mmc/core/pwrseq_sd8787.c
@@ -14,6 +14,7 @@
 #include <linux/kernel.h>
 #include <linux/platform_device.h>
 #include <linux/module.h>
+#include <linux/property.h>
 #include <linux/slab.h>
 #include <linux/device.h>
 #include <linux/err.h>
@@ -27,6 +28,7 @@ struct mmc_pwrseq_sd8787 {
 	struct mmc_pwrseq pwrseq;
 	struct gpio_desc *reset_gpio;
 	struct gpio_desc *pwrdn_gpio;
+	u32 reset_pwrdwn_delay_ms;
 };
 
 #define to_pwrseq_sd8787(p) container_of(p, struct mmc_pwrseq_sd8787, pwrseq)
@@ -37,7 +39,7 @@ static void mmc_pwrseq_sd8787_pre_power_on(struct mmc_host *host)
 
 	gpiod_set_value_cansleep(pwrseq->reset_gpio, 1);
 
-	msleep(300);
+	msleep(pwrseq->reset_pwrdwn_delay_ms);
 	gpiod_set_value_cansleep(pwrseq->pwrdn_gpio, 1);
 }
 
@@ -64,6 +66,7 @@ static int mmc_pwrseq_sd8787_probe(struct platform_device *pdev)
 {
 	struct mmc_pwrseq_sd8787 *pwrseq;
 	struct device *dev = &pdev->dev;
+	int ret;
 
 	pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
 	if (!pwrseq)
@@ -77,6 +80,12 @@ static int mmc_pwrseq_sd8787_probe(struct platform_device *pdev)
 	if (IS_ERR(pwrseq->reset_gpio))
 		return PTR_ERR(pwrseq->reset_gpio);
 
+	ret = device_property_read_u32(dev, "reset-power-delay-ms",
+				       &pwrseq->reset_pwrdwn_delay_ms);
+	/* Keep compatibility with old devices. */
+	if (ret)
+		pwrseq->reset_pwrdwn_delay_ms = 300;
+
 	pwrseq->pwrseq.dev = dev;
 	pwrseq->pwrseq.ops = &mmc_pwrseq_sd8787_ops;
 	pwrseq->pwrseq.owner = THIS_MODULE;
-- 
2.25.1