[PATCH v2] pinctrl: aspeed: Fix ast2500 strap register write logic

[Yong Li]

On AST2500, the hardware strap register(SCU70) only accepts write ‘1’,
to clear it to ‘0’, must set bits(write  ‘1’) to SCU7C

Signed-off-by: Yong Li <sdliy...@gmail.com>
---
 drivers/pinctrl/aspeed/pinctrl-aspeed.c | 20 ++++++++++++++++++--
 drivers/pinctrl/aspeed/pinctrl-aspeed.h |  1 +
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/pinctrl/aspeed/pinctrl-aspeed.c 
b/drivers/pinctrl/aspeed/pinctrl-aspeed.c
index a86a4d6..9d2b2e9 100644
--- a/drivers/pinctrl/aspeed/pinctrl-aspeed.c
+++ b/drivers/pinctrl/aspeed/pinctrl-aspeed.c
@@ -183,6 +183,7 @@ static int aspeed_sig_expr_set(const struct aspeed_sig_expr 
*expr,
 {
        int ret;
        int i;
+       unsigned int rev_id;
 
        for (i = 0; i < expr->ndescs; i++) {
                const struct aspeed_sig_desc *desc = &expr->descs[i];
@@ -213,8 +214,23 @@ static int aspeed_sig_expr_set(const struct 
aspeed_sig_expr *expr,
                if (desc->ip == ASPEED_IP_SCU && desc->reg == HW_STRAP2)
                        continue;
 
-               ret = regmap_update_bits(maps[desc->ip], desc->reg,
-                                        desc->mask, val);
+               /* On AST2500, Set bits in SCU7C are cleared from SCU70 */
+               if (desc->ip == ASPEED_IP_SCU && desc->reg == HW_STRAP1 &&
+                       val == 0) {
+                       ret = regmap_read(maps[ASPEED_IP_SCU],
+                               HW_REVISION_ID, &rev_id);
+                       if (ret < 0)
+                               return ret;
+
+                       if (0x04 == ((rev_id >> 24) & 0xff))
+                               ret = regmap_update_bits(maps[desc->ip],
+                                       HW_REVISION_ID, desc->mask, desc->mask);
+                       else
+                               ret = regmap_update_bits(maps[desc->ip],
+                                       desc->reg, desc->mask, val);
+               } else
+                       ret = regmap_update_bits(maps[desc->ip], desc->reg,
+                               desc->mask, val);
 
                if (ret)
                        return ret;
diff --git a/drivers/pinctrl/aspeed/pinctrl-aspeed.h 
b/drivers/pinctrl/aspeed/pinctrl-aspeed.h
index fa125db..d4d7f03 100644
--- a/drivers/pinctrl/aspeed/pinctrl-aspeed.h
+++ b/drivers/pinctrl/aspeed/pinctrl-aspeed.h
@@ -251,6 +251,7 @@
 #define SCU3C           0x3C /* System Reset Control/Status Register */
 #define SCU48           0x48 /* MAC Interface Clock Delay Setting */
 #define HW_STRAP1       0x70 /* AST2400 strapping is 33 bits, is split */
+#define HW_REVISION_ID  0x7C /* Silicon revision ID register */
 #define SCU80           0x80 /* Multi-function Pin Control #1 */
 #define SCU84           0x84 /* Multi-function Pin Control #2 */
 #define SCU88           0x88 /* Multi-function Pin Control #3 */
-- 
2.7.4