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Subject[PATCH v2 4/8] mtd: maps: gpio-addr-flash: Use order insted of size
Date
By using the order of the window instead of the size, we can replace a
lot of expensive division and modulus on the code with simple bit
operations.

Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
---
drivers/mtd/maps/gpio-addr-flash.c | 39 ++++++++++++++++--------------
1 file changed, 21 insertions(+), 18 deletions(-)

diff --git a/drivers/mtd/maps/gpio-addr-flash.c b/drivers/mtd/maps/gpio-addr-flash.c
index 54a0d7d2365a..22e100f07112 100644
--- a/drivers/mtd/maps/gpio-addr-flash.c
+++ b/drivers/mtd/maps/gpio-addr-flash.c
@@ -25,6 +25,8 @@
#include <linux/slab.h>
#include <linux/types.h>

+#define win_mask(x) ((BIT(x)) - 1)
+
#define DRIVER_NAME "gpio-addr-flash"

/**
@@ -34,7 +36,7 @@
* @gpio_count: number of GPIOs used to address
* @gpio_addrs: array of GPIOs to twiddle
* @gpio_values: cached GPIO values
- * @win_size: dedicated memory size (if no GPIOs)
+ * @win_order: dedicated memory size (if no GPIOs)
*/
struct async_state {
struct mtd_info *mtd;
@@ -42,7 +44,7 @@ struct async_state {
size_t gpio_count;
unsigned *gpio_addrs;
int *gpio_values;
- unsigned long win_size;
+ unsigned int win_order;
};
#define gf_map_info_to_state(mi) ((struct async_state *)(mi)->map_priv_1)

@@ -60,7 +62,8 @@ static void gf_set_gpios(struct async_state *state, unsigned long ofs)
{
size_t i = 0;
int value;
- ofs /= state->win_size;
+
+ ofs >>= state->win_order;
do {
value = ofs & (1 << i);
if (state->gpio_values[i] != value) {
@@ -83,7 +86,7 @@ static map_word gf_read(struct map_info *map, unsigned long ofs)

gf_set_gpios(state, ofs);

- word = readw(map->virt + (ofs % state->win_size));
+ word = readw(map->virt + (ofs & win_mask(state->win_order)));
test.x[0] = word;
return test;
}
@@ -105,14 +108,14 @@ static void gf_copy_from(struct map_info *map, void *to, unsigned long from, ssi
int this_len;

while (len) {
- if ((from % state->win_size) + len > state->win_size)
- this_len = state->win_size - (from % state->win_size);
- else
- this_len = len;
+ this_len = from & win_mask(state->win_order);
+ this_len = BIT(state->win_order) - this_len;
+ this_len = min_t(int, len, this_len);

gf_set_gpios(state, from);
- memcpy_fromio(to, map->virt + (from % state->win_size),
- this_len);
+ memcpy_fromio(to,
+ map->virt + (from & win_mask(state->win_order)),
+ this_len);
len -= this_len;
from += this_len;
to += this_len;
@@ -132,7 +135,7 @@ static void gf_write(struct map_info *map, map_word d1, unsigned long ofs)
gf_set_gpios(state, ofs);

d = d1.x[0];
- writew(d, map->virt + (ofs % state->win_size));
+ writew(d, map->virt + (ofs & win_mask(state->win_order)));
}

/**
@@ -152,13 +155,13 @@ static void gf_copy_to(struct map_info *map, unsigned long to,
int this_len;

while (len) {
- if ((to % state->win_size) + len > state->win_size)
- this_len = state->win_size - (to % state->win_size);
- else
- this_len = len;
+ this_len = to & win_mask(state->win_order);
+ this_len = BIT(state->win_order) - this_len;
+ this_len = min_t(int, len, this_len);

gf_set_gpios(state, to);
- memcpy_toio(map->virt + (to % state->win_size), from, len);
+ memcpy_toio(map->virt + (to & win_mask(state->win_order)),
+ from, len);

len -= this_len;
to += this_len;
@@ -224,7 +227,7 @@ static int gpio_flash_probe(struct platform_device *pdev)
state->gpio_count = gpios->end;
state->gpio_addrs = (void *)(unsigned long)gpios->start;
state->gpio_values = (void *)(state + 1);
- state->win_size = resource_size(memory);
+ state->win_order = get_bitmask_order(resource_size(memory)) - 1;
memset(state->gpio_values, 0xff, arr_size);

state->map.name = DRIVER_NAME;
@@ -233,7 +236,7 @@ static int gpio_flash_probe(struct platform_device *pdev)
state->map.write = gf_write;
state->map.copy_to = gf_copy_to;
state->map.bankwidth = pdata->width;
- state->map.size = state->win_size * (1 << state->gpio_count);
+ state->map.size = BIT(state->win_order + state->gpio_count);
state->map.virt = devm_ioremap_resource(&pdev->dev, memory);
if (IS_ERR(state->map.virt)) {
dev_err(&pdev->dev, "failed to map memory\n");
--
2.18.0
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