[RESEND,v4,3/3] gpio: xilinx: Utilize generic bitmap_get_value and _set_value

Commit Message

Syed Nayyar Waris April 2, 2021, 4:37 p.m. UTC

This patch reimplements the xgpio_set_multiple() function in
drivers/gpio/gpio-xilinx.c to use the new generic functions:
bitmap_get_value() and bitmap_set_value(). The code is now simpler
to read and understand. Moreover, instead of looping for each bit
in xgpio_set_multiple() function, now we can check each channel at
a time and save cycles.

Cc: Bartosz Golaszewski <[e-mail]>
Cc: Michal Simek <[e-mail]>
Signed-off-by: Syed Nayyar Waris <[e-mail]>
Acked-by: William Breathitt Gray <[e-mail]>
---
 drivers/gpio/gpio-xilinx.c | 52 +++++++++++++++++++-------------------
 1 file changed, 26 insertions(+), 26 deletions(-)

Comments

Andy Shevchenko April 8, 2021, 1:44 p.m. UTC | #1

On Fri, Apr 02, 2021 at 10:07:36PM +0530, Syed Nayyar Waris wrote:
> This patch reimplements the xgpio_set_multiple() function in
> drivers/gpio/gpio-xilinx.c to use the new generic functions:
> bitmap_get_value() and bitmap_set_value(). The code is now simpler
> to read and understand. Moreover, instead of looping for each bit
> in xgpio_set_multiple() function, now we can check each channel at
> a time and save cycles.

As promised, I have looked at this with a fresh eye and NAK from me. Sorry.
This is less than a half baked solution. I spent couple of evenings, so
I'll come up with full conversion of this driver to the bitmap API.
And yes, as I have told you like half a year before, bitmap_get_value32() and
bitmap_set_value32() is much more useful (and I actually implemented them
locally for the sake of conversion).

So, summarize this I do not think we have real users of the proposed API.

Patch

diff --git a/drivers/gpio/gpio-xilinx.c b/drivers/gpio/gpio-xilinx.c
index b411d3156e0b..512198250b02 100644
--- a/drivers/gpio/gpio-xilinx.c
+++ b/drivers/gpio/gpio-xilinx.c
@@ -18,6 +18,7 @@ 
 #include <linux/of_platform.h>
 #include <linux/pm_runtime.h>
 #include <linux/slab.h>
+#include "gpiolib.h"
 
 /* Register Offset Definitions */
 #define XGPIO_DATA_OFFSET   (0x0)	/* Data register  */
@@ -161,35 +162,34 @@  static void xgpio_set_multiple(struct gpio_chip *gc, unsigned long *mask,
 {
 	unsigned long flags;
 	struct xgpio_instance *chip = gpiochip_get_data(gc);
-	int index = xgpio_index(chip, 0);
-	int offset, i;
 
-	spin_lock_irqsave(&chip->gpio_lock, flags);
+	u32 *state = chip->gpio_state;
+	unsigned int *width = chip->gpio_width;
+	DECLARE_BITMAP(old, 64);
+	DECLARE_BITMAP(new, 64);
+	DECLARE_BITMAP(changed, 64);
 
-	/* Write to GPIO signals */
-	for (i = 0; i < gc->ngpio; i++) {
-		if (*mask == 0)
-			break;
-		/* Once finished with an index write it out to the register */
-		if (index !=  xgpio_index(chip, i)) {
-			xgpio_writereg(chip->regs + XGPIO_DATA_OFFSET +
-				       index * XGPIO_CHANNEL_OFFSET,
-				       chip->gpio_state[index]);
-			spin_unlock_irqrestore(&chip->gpio_lock, flags);
-			index =  xgpio_index(chip, i);
-			spin_lock_irqsave(&chip->gpio_lock, flags);
-		}
-		if (__test_and_clear_bit(i, mask)) {
-			offset =  xgpio_offset(chip, i);
-			if (test_bit(i, bits))
-				chip->gpio_state[index] |= BIT(offset);
-			else
-				chip->gpio_state[index] &= ~BIT(offset);
-		}
-	}
+	spin_lock_irqsave(&chip->gpio_lock, flags);
 
-	xgpio_writereg(chip->regs + XGPIO_DATA_OFFSET +
-		       index * XGPIO_CHANNEL_OFFSET, chip->gpio_state[index]);
+	/* Copy initial value of state bits into 'old' contiguously */
+	bitmap_set_value(old, 64, state[0], width[0], 0);
+	bitmap_set_value(old, 64, state[1], width[1], width[0]);
+	/* Copy value from 'old' into 'new' with mask applied */
+	bitmap_replace(new, old, bits, mask, gc->ngpio);
+
+	bitmap_from_arr32(old, state, 64);
+	/* Update 'state' */
+	state[0] = bitmap_get_value(new, 0, width[0]);
+	state[1] = bitmap_get_value(new, width[0], width[1]);
+	bitmap_from_arr32(new, state, 64);
+	/* XOR operation sets only changed bits */
+	bitmap_xor(changed, old, new, 64);
+
+	if (((u32 *)changed)[0])
+		xgpio_writereg(chip->regs + XGPIO_DATA_OFFSET, state[0]);
+	if (((u32 *)changed)[1])
+		xgpio_writereg(chip->regs + XGPIO_DATA_OFFSET +
+			XGPIO_CHANNEL_OFFSET, state[1]);
 
 	spin_unlock_irqrestore(&chip->gpio_lock, flags);
 }