[PATCH 2/2 V5] regmap: Apply optional delay in multi_reg_write/register_patch

Nariman Poushin
2015-07-16T15:36:33Z

Add an optional delay_us field in reg_sequence to allow the client to
specify a delay (in microseconds) to be applied after any given write
in a sequence of writes.

We treat a delay in a sequence the same way we treat a page change as
they are logically similar in that you can coalesce all write before
a delay (in the same way you can coalesce all writes before a page
change is needed)

Signed-off-by: Nariman Poushin <nariman@opensource.wolfsonmicro.com>
---
drivers/base/regmap/regmap.c | 54 +++++++++++++++++++++++++++++++++++++++-----
include/linux/regmap.h | 5 +++-
2 files changed, 52 insertions(+), 7 deletions(-)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 0a849ee..fd4dac9 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -18,6 +18,7 @@
#include <linux/of.h>
#include <linux/rbtree.h>
#include <linux/sched.h>
+#include <linux/delay.h>

#define CREATE_TRACE_POINTS
#include "trace.h"
@@ -1819,10 +1820,12 @@ static int _regmap_range_multi_paged_reg_write(struct regmap *map,
int i, n;
struct reg_sequence *base;
unsigned int this_page = 0;
+ unsigned int page_change = 0;
/*
* the set of registers are not neccessarily in order, but
* since the order of write must be preserved this algorithm
- * chops the set each time the page changes
+ * chops the set each time the page changes. This also applies
+ * if there is a delay required at any point in the sequence.
*/
base = regs;
for (i = 0, n = 0; i < num_regs; i++, n++) {
@@ -1838,16 +1841,48 @@ static int _regmap_range_multi_paged_reg_write(struct regmap *map,
this_page = win_page;
if (win_page != this_page) {
this_page = win_page;
+ page_change = 1;
+ }
+ }
+
+ /* If we have both a page change and a delay make sure to
+ * write the regs and apply the delay before we change the
+ * page.
+ */
+
+ if (page_change || regs[i].delay_us) {
+
+ /* For situations where the first write requires
+ * a delay we need to make sure we don't call
+ * raw_multi_reg_write with n=0
+ * This can't occur with page breaks as we
+ * never write on the first iteration
+ */
+ if (regs[i].delay_us && i == 0)
+ n = 1;
+
ret = _regmap_raw_multi_reg_write(map, base, n);
if (ret != 0)
return ret;
+
+ if (regs[i].delay_us)
+ udelay(regs[i].delay_us);
+
base += n;
n = 0;
- }
- ret = _regmap_select_page(map, &base[n].reg, range, 1);
- if (ret != 0)
- return ret;
+
+ if (page_change) {
+ ret = _regmap_select_page(map,
+ &base[n].reg,
+ range, 1);
+ if (ret != 0)
+ return ret;
+
+ page_change = 0;
+ }
+
}
+
}
if (n > 0)
return _regmap_raw_multi_reg_write(map, base, n);
@@ -1866,6 +1901,9 @@ static int _regmap_multi_reg_write(struct regmap *map,
ret = _regmap_write(map, regs[i].reg, regs[i].def);
if (ret != 0)
return ret;
+
+ if (regs[i].delay_us)
+ udelay(regs[i].delay_us);
}
return 0;
}
@@ -1905,8 +1943,12 @@ static int _regmap_multi_reg_write(struct regmap *map,
for (i = 0; i < num_regs; i++) {
unsigned int reg = regs[i].reg;
struct regmap_range_node *range;
+
+ /* Coalesce all the writes between a page break or a delay
+ * in a sequence
+ */
range = _regmap_range_lookup(map, reg);
- if (range) {
+ if (range || regs[i].delay_us) {
size_t len = sizeof(struct reg_sequence)*num_regs;
struct reg_sequence *base = kmemdup(regs, len,
GFP_KERNEL);
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 4a67590..e32c28c 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -51,14 +51,17 @@ struct reg_default {
};

/**
- * Register/value pairs for sequences of writes
+ * Register/value pairs for sequences of writes with an optional delay in
+ * microseconds to be applied after each write.
*
* @reg: Register address.
* @def: Register value.
+ * @delay_us: Delay to be applied after the register write in microseconds
*/
struct reg_sequence {
unsigned int reg;
unsigned int def;
+ unsigned int delay_us;