Hello Roger,

On Fri, 2022-10-07 at 14:03 +0300, Roger Quadros wrote:

Hello Benedikt,

Thanks for doing the changes but still a few comments. ;)

On 05/10/2022 17:22, B. Niedermayr wrote:

quoted

From: Benedikt Niedermayr <benedikt.niedermayr@siemens.com>

This patch introduces support for setting the wait-pin polarity as well
as using the same wait-pin for different CS regions.

The waitpin polarity can be configured via the WAITPIN<X>POLARITY bits
in the GPMC_CONFIG register. This is currently not supported by the
driver. This patch adds support for setting the required register bits
with the "ti,wait-pin-polarity" dt-property.

The wait-pin can also be shared between different CS regions for special
usecases. Therefore GPMC must keep track of wait-pin allocations, so it
knows that either GPMC itself or another driver has the ownership.

Signed-off-by: Benedikt Niedermayr <benedikt.niedermayr@siemens.com>
---
 drivers/memory/omap-gpmc.c              | 122 +++++++++++++++++++++---
 include/linux/platform_data/gpmc-omap.h |   8 ++
 2 files changed, 117 insertions(+), 13 deletions(-)

diff --git a/drivers/memory/omap-gpmc.c b/drivers/memory/omap-gpmc.c
index d9bf1c2ac319..95c4e61753c0 100644
--- a/drivers/memory/omap-gpmc.c
+++ b/drivers/memory/omap-gpmc.c

@@ -132,6 +132,7 @@
 #define GPMC_CONFIG_DEV_SIZE	0x00000002
 #define GPMC_CONFIG_DEV_TYPE	0x00000003
 
+#define GPMC_CONFIG_WAITPINPOLARITY(pin)	(BIT(pin) << 8)
 #define GPMC_CONFIG1_WRAPBURST_SUPP     (1 << 31)
 #define GPMC_CONFIG1_READMULTIPLE_SUPP  (1 << 30)
 #define GPMC_CONFIG1_READTYPE_ASYNC     (0 << 29)

@@ -227,11 +228,18 @@ struct omap3_gpmc_regs {
 	struct gpmc_cs_config cs_context[GPMC_CS_NUM];
 };
 
+struct gpmc_waitpin {
+	u32 pin;
+	u32 polarity;
+	struct gpio_desc *desc;
+};
+
 struct gpmc_device {
 	struct device *dev;
 	int irq;
 	struct irq_chip irq_chip;
 	struct gpio_chip gpio_chip;
+	struct gpmc_waitpin *waitpins;
 	int nirqs;
 	struct resource *data;
 };

@@ -1030,6 +1038,62 @@ void gpmc_cs_free(int cs)
 }
 EXPORT_SYMBOL(gpmc_cs_free);
 
+static bool gpmc_is_valid_waitpin(u32 waitpin)
+{
+	return waitpin >= 0 && waitpin < gpmc_nr_waitpins;
+}
+
+static int gpmc_alloc_waitpin(struct gpmc_device *gpmc,
+			      struct gpmc_settings *p)
+{
+	int ret;
+	struct gpmc_waitpin *waitpin;
+	struct gpio_desc *waitpin_desc;
+
+	if (!gpmc_is_valid_waitpin(p->wait_pin))
+		return -EINVAL;
+
+	waitpin = &gpmc->waitpins[p->wait_pin];
+
+	/* Reserve the GPIO for wait pin usage.
+	 * GPIO polarity doesn't matter here. Wait pin polarity
+	 * is set in GPMC_CONFIG register.
+	 */
+	waitpin_desc = gpiochip_request_own_desc(&gpmc->gpio_chip,
+						 p->wait_pin, "WAITPIN",
+						 GPIO_ACTIVE_HIGH,
+						 GPIOD_IN);
+
+	ret = PTR_ERR(waitpin_desc);
+	if (IS_ERR(waitpin_desc) && ret != -EBUSY)
+		return ret;

We don't want to request a new GPIO descriptor if waiptin->desc is already present
which means it was requested before.

So let's move the above gpiochip_request_own_desc() call and error check to inside
the below if {}.

quoted

+
+	if (!waitpin->desc) {
+		/* New wait pin */

here --->

Ok that makes sense. I will change that.

quoted

+		waitpin->desc = waitpin_desc;
+		waitpin->pin = p->wait_pin;
+		waitpin->polarity = p->wait_pin_polarity;
+	} else {
+		/* Shared wait pin */
+		if (p->wait_pin_polarity != waitpin->polarity ||
+		    p->wait_pin != waitpin->pin) {
+			dev_err(gpmc->dev,
+				"shared-wait-pin: invalid configuration\n");
+			return -EINVAL;
+		}
+		dev_info(gpmc->dev, "shared wait-pin: %d\n", waitpin->pin);
+	}
+
+	return 0;
+}
+
+static void gpmc_free_waitpin(struct gpmc_device *gpmc,
+			      int wait_pin)
+{
+	if (gpmc_is_valid_waitpin(wait_pin))
+		gpiochip_free_own_desc(gpmc->waitpins[wait_pin].desc);
+}
+
 /**
  * gpmc_configure - write request to configure gpmc
  * @cmd: command type

@@ -1881,6 +1945,17 @@ int gpmc_cs_program_settings(int cs, struct gpmc_settings *p)
 
 	gpmc_cs_write_reg(cs, GPMC_CS_CONFIG1, config1);
 
+	if (p->wait_pin_polarity != GPMC_WAITPINPOLARITY_INVALID) {
+		config1 = gpmc_read_reg(GPMC_CONFIG);
+
+		if (p->wait_pin_polarity == GPMC_WAITPINPOLARITY_ACTIVE_LOW)
+			config1 &= ~GPMC_CONFIG_WAITPINPOLARITY(p->wait_pin);
+		else if (p->wait_pin_polarity == GPMC_WAITPINPOLARITY_ACTIVE_HIGH)
+			config1 |= GPMC_CONFIG_WAITPINPOLARITY(p->wait_pin);
+
+		gpmc_write_reg(GPMC_CONFIG, config1);
+	}
+
 	return 0;
 }
 

@@ -1980,7 +2055,25 @@ void gpmc_read_settings_dt(struct device_node *np, struct gpmc_settings *p)
 				__func__);
 	}
 
+	p->wait_pin = GPMC_WAITPIN_DEFAULT;
+	p->wait_pin_polarity = GPMC_WAITPINPOLARITY_INVALID;
+
 	if (!of_property_read_u32(np, "gpmc,wait-pin", &p->wait_pin)) {
+		if (!gpmc_is_valid_waitpin(p->wait_pin)) {
+			pr_err("%s: Invalid wait-pin (%d)\n", __func__, p->wait_pin);
+			p->wait_pin = GPMC_WAITPIN_DEFAULT;
+		}
+
+		if (!of_property_read_u32(np, "gpmc,wait-pin-polarity",

"ti,wait-pin-polarity" to match what you put in the DT bindings document?

Upps. That's a dump mistake. I thought I tested it. But I only looked at the dmesg output without 
actually checking the CONFIG register afterwards.
We made the property optional which doesn't lead to errors in case we're not using it....

I will change that.

quoted

+					  &p->wait_pin_polarity)) {
+			if (p->wait_pin_polarity != GPMC_WAITPINPOLARITY_ACTIVE_HIGH &&
+			    p->wait_pin_polarity != GPMC_WAITPINPOLARITY_ACTIVE_LOW) {
+				pr_err("%s: Invalid wait-pin-polarity (%d)\n",
+				       __func__, p->wait_pin_polarity);
+				p->wait_pin_polarity = GPMC_WAITPINPOLARITY_INVALID;
+				}
+		}
+
 		p->wait_on_read = of_property_read_bool(np,
 							"gpmc,wait-on-read");
 		p->wait_on_write = of_property_read_bool(np,

@@ -2085,7 +2178,6 @@ static int gpmc_probe_generic_child(struct platform_device *pdev,
 	const char *name;
 	int ret, cs;
 	u32 val;
-	struct gpio_desc *waitpin_desc = NULL;
 	struct gpmc_device *gpmc = platform_get_drvdata(pdev);
 
 	if (of_property_read_u32(child, "reg", &cs) < 0) {

@@ -2214,17 +2306,9 @@ static int gpmc_probe_generic_child(struct platform_device *pdev,
 
 	/* Reserve wait pin if it is required and valid */
 	if (gpmc_s.wait_on_read || gpmc_s.wait_on_write) {
-		unsigned int wait_pin = gpmc_s.wait_pin;
-
-		waitpin_desc = gpiochip_request_own_desc(&gpmc->gpio_chip,
-							 wait_pin, "WAITPIN",
-							 GPIO_ACTIVE_HIGH,
-							 GPIOD_IN);
-		if (IS_ERR(waitpin_desc)) {
-			dev_err(&pdev->dev, "invalid wait-pin: %d\n", wait_pin);
-			ret = PTR_ERR(waitpin_desc);
+		ret = gpmc_alloc_waitpin(gpmc, &gpmc_s);
+		if (ret < 0)
 			goto err;
-		}
 	}
 
 	gpmc_cs_show_timings(cs, "before gpmc_cs_program_settings");

@@ -2268,7 +2352,7 @@ static int gpmc_probe_generic_child(struct platform_device *pdev,
 	ret = -ENODEV;
 
 err_cs:
-	gpiochip_free_own_desc(waitpin_desc);
+	gpmc_free_waitpin(gpmc, gpmc_s.wait_pin);
 err:
 	gpmc_cs_free(cs);
 

@@ -2395,7 +2479,7 @@ static int gpmc_gpio_init(struct gpmc_device *gpmc)
 
 static int gpmc_probe(struct platform_device *pdev)
 {
-	int rc;
+	int rc, i;
 	u32 l;
 	struct resource *res;
 	struct gpmc_device *gpmc;

@@ -2455,6 +2539,15 @@ static int gpmc_probe(struct platform_device *pdev)
 		gpmc_nr_waitpins = GPMC_NR_WAITPINS;
 	}
 
+	gpmc->waitpins = devm_kzalloc(&pdev->dev,
+				      gpmc_nr_waitpins * sizeof(struct gpmc_waitpin),
+				      GFP_KERNEL);
+	if (!gpmc->waitpins)
+		return -ENOMEM;
+
+	for (i = 0; i < gpmc_nr_waitpins; i++)
+		gpmc->waitpins[i].pin = GPMC_WAITPIN_DEFAULT;
+
 	pm_runtime_enable(&pdev->dev);
 	pm_runtime_get_sync(&pdev->dev);
 

@@ -2505,8 +2598,11 @@ static int gpmc_probe(struct platform_device *pdev)
 
 static int gpmc_remove(struct platform_device *pdev)
 {
+	int i;
 	struct gpmc_device *gpmc = platform_get_drvdata(pdev);
 
+	for (i = 0; i < gpmc_nr_waitpins; i++)
+		gpmc_free_waitpin(gpmc, i);
 	gpmc_free_irq(gpmc);
 	gpmc_mem_exit();
 	pm_runtime_put_sync(&pdev->dev);

diff --git a/include/linux/platform_data/gpmc-omap.h b/include/linux/platform_data/gpmc-omap.h
index c9cc4e32435d..9aa47dd9b6c6 100644
--- a/include/linux/platform_data/gpmc-omap.h
+++ b/include/linux/platform_data/gpmc-omap.h

@@ -136,6 +136,13 @@ struct gpmc_device_timings {
 #define GPMC_MUX_AAD			1	/* Addr-Addr-Data multiplex */
 #define GPMC_MUX_AD			2	/* Addr-Data multiplex */
 
+/* Wait pin polarity values */
+#define GPMC_WAITPINPOLARITY_INVALID -1
+#define GPMC_WAITPINPOLARITY_ACTIVE_LOW 0
+#define GPMC_WAITPINPOLARITY_ACTIVE_HIGH 1
+
+#define GPMC_WAITPIN_DEFAULT -1

Sorry I missed this one last time. I think it should be called GPMC_WAITPIN_INVALID.

So I will change GPMC_WAITPIN_DEFAULT -> GPMC_WAITPIN_INVALID as well.

quoted

+
 struct gpmc_settings {
 	bool burst_wrap;	/* enables wrap bursting */
 	bool burst_read;	/* enables read page/burst mode */

@@ -149,6 +156,7 @@ struct gpmc_settings {
 	u32 device_width;	/* device bus width (8 or 16 bit) */
 	u32 mux_add_data;	/* multiplex address & data */
 	u32 wait_pin;		/* wait-pin to be used */
+	u32 wait_pin_polarity;
 };
 
 /* Data for each chip select */

cheers,
-roger

cheers,
benedikt