diff mbox series

[2/2] gpio: xilinx: Add support for no initialisation at probe

Message ID 1525338346-31684-2-git-send-email-shubhrajyoti.datta@gmail.com
State New
Headers show
Series [1/2] dt-bindings: gpio-xilinx: Update no-init property | expand

Commit Message

Shubhrajyoti Datta May 3, 2018, 9:05 a.m. UTC 
From: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>

Add a dt property to indicate no initialisation at probe.
In some cases the user may want no initialisation of the
gpios. For example PS only reset the user may not want the
re-initialisation of the ip.

Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
---
 drivers/gpio/gpio-xilinx.c | 44 ++++++++++++++++++++++++++++++++++----------
 1 file changed, 34 insertions(+), 10 deletions(-)

Comments

Linus Walleij May 16, 2018, 12:14 p.m. UTC | #1 
On Thu, May 3, 2018 at 11:05 AM,  <shubhrajyoti.datta@gmail.com> wrote:

> From: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
>
> Add a dt property to indicate no initialisation at probe.
> In some cases the user may want no initialisation of the
> gpios. For example PS only reset the user may not want the
> re-initialisation of the ip.
>
> Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>

Usually the recommendation is to leave electronics in the
power-on-state until their state is explicitly changed.

Is it possible to just make the new "no-init" behaviour
the default? Do we even need to keep the initialization code?

Michal?

Yours,
Linus Walleij
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diff mbox series

Patch

diff --git a/drivers/gpio/gpio-xilinx.c b/drivers/gpio/gpio-xilinx.c
index e8ec0e3..06988f1 100644
--- a/drivers/gpio/gpio-xilinx.c
+++ b/drivers/gpio/gpio-xilinx.c
@@ -41,6 +41,7 @@ 
 /**
  * struct xgpio_instance - Stores information about GPIO device
  * @mmchip: OF GPIO chip for memory mapped banks
+ * @no_init: No intitialisation at probe
  * @gpio_width: GPIO width for every channel
  * @gpio_state: GPIO state shadow register
  * @gpio_dir: GPIO direction shadow register
@@ -48,6 +49,7 @@ 
  */
 struct xgpio_instance {
 	struct of_mm_gpio_chip mmchip;
+	bool no_init;
 	unsigned int gpio_width[2];
 	u32 gpio_state[2];
 	u32 gpio_dir[2];
@@ -257,16 +259,36 @@  static void xgpio_save_regs(struct of_mm_gpio_chip *mm_gc)
 	struct xgpio_instance *chip =
 		container_of(mm_gc, struct xgpio_instance, mmchip);
 
-	xgpio_writereg(mm_gc->regs + XGPIO_DATA_OFFSET,	chip->gpio_state[0]);
-	xgpio_writereg(mm_gc->regs + XGPIO_TRI_OFFSET, chip->gpio_dir[0]);
-
-	if (!chip->gpio_width[1])
-		return;
-
-	xgpio_writereg(mm_gc->regs + XGPIO_DATA_OFFSET + XGPIO_CHANNEL_OFFSET,
-		       chip->gpio_state[1]);
-	xgpio_writereg(mm_gc->regs + XGPIO_TRI_OFFSET + XGPIO_CHANNEL_OFFSET,
-		       chip->gpio_dir[1]);
+	if (chip->no_init) {
+		chip->gpio_state[0] = xgpio_readreg(mm_gc->regs +
+						    XGPIO_DATA_OFFSET);
+		chip->gpio_dir[0] =  xgpio_readreg(mm_gc->regs +
+						   XGPIO_TRI_OFFSET);
+
+		if (!chip->gpio_width[1])
+			return;
+
+		chip->gpio_state[1] = xgpio_readreg(mm_gc->regs +
+						    XGPIO_DATA_OFFSET +
+						    XGPIO_CHANNEL_OFFSET);
+		chip->gpio_dir[1] = xgpio_readreg(mm_gc->regs +
+						   XGPIO_TRI_OFFSET +
+						   XGPIO_CHANNEL_OFFSET);
+
+	} else {
+		xgpio_writereg(mm_gc->regs + XGPIO_DATA_OFFSET,
+			       chip->gpio_state[0]);
+		xgpio_writereg(mm_gc->regs + XGPIO_TRI_OFFSET,
+			       chip->gpio_dir[0]);
+
+		if (!chip->gpio_width[1])
+			return;
+
+		xgpio_writereg(mm_gc->regs + XGPIO_DATA_OFFSET +
+			       XGPIO_CHANNEL_OFFSET, chip->gpio_state[1]);
+		xgpio_writereg(mm_gc->regs + XGPIO_TRI_OFFSET +
+			       XGPIO_CHANNEL_OFFSET, chip->gpio_dir[1]);
+	}
 }
 
 /**
@@ -323,6 +345,8 @@  static int xgpio_probe(struct platform_device *pdev)
 
 	spin_lock_init(&chip->gpio_lock[0]);
 
+	chip->no_init = of_property_read_bool(np, "xlnx,no-init");
+
 	if (of_property_read_u32(np, "xlnx,is-dual", &is_dual))
 		is_dual = 0;