[lm-sensors] [PATCH 4/6] hwmon: (w83627ehf) Optimize multi-bank register access

Guenter Roeck guenter.roeck at ericsson.com
Thu Feb 10 04:35:50 CET 2011


Assume that each register is banked, and set the bank for each access.
Cache the bank number so it only needs to be set if it changes.
---
 drivers/hwmon/w83627ehf.c |   26 +++++++++++---------------
 1 files changed, 11 insertions(+), 15 deletions(-)

diff --git a/drivers/hwmon/w83627ehf.c b/drivers/hwmon/w83627ehf.c
index dcdd843..7a71425 100644
--- a/drivers/hwmon/w83627ehf.c
+++ b/drivers/hwmon/w83627ehf.c
@@ -304,6 +304,7 @@ struct w83627ehf_data {
 	unsigned long last_updated;	/* In jiffies */
 
 	/* Register values */
+	u8 bank;		/* current register bank */
 	u8 in_num;		/* number of in inputs we have */
 	u8 in[10];		/* Register value */
 	u8 in_max[10];		/* Register value */
@@ -347,21 +348,19 @@ struct w83627ehf_sio_data {
 	enum kinds kind;
 };
 
-/* Registers 0x50-0x5f are banked */
+/*
+ * On older chips, only registers 0x50-0x5f are banked.
+ * On more recent chips, all registers are banked.
+ * Assume that is the case and set the bank number for each access.
+ * Cache the bank number so it only needs to be set if it changes.
+ */
 static inline void w83627ehf_set_bank(struct w83627ehf_data *data, u16 reg)
 {
-	if ((reg & 0x00f0) == 0x50) {
-		outb_p(W83627EHF_REG_BANK, data->addr + ADDR_REG_OFFSET);
-		outb_p(reg >> 8, data->addr + DATA_REG_OFFSET);
-	}
-}
-
-/* Not strictly necessary, but play it safe for now */
-static inline void w83627ehf_reset_bank(struct w83627ehf_data *data, u16 reg)
-{
-	if (reg & 0xff00) {
+	u8 bank = reg >> 8;
+	if (data->bank != bank) {
 		outb_p(W83627EHF_REG_BANK, data->addr + ADDR_REG_OFFSET);
-		outb_p(0, data->addr + DATA_REG_OFFSET);
+		outb_p(bank, data->addr + DATA_REG_OFFSET);
+		data->bank = bank;
 	}
 }
 
@@ -379,10 +378,8 @@ static u16 w83627ehf_read_value(struct w83627ehf_data *data, u16 reg)
 		       data->addr + ADDR_REG_OFFSET);
 		res = (res << 8) + inb_p(data->addr + DATA_REG_OFFSET);
 	}
-	w83627ehf_reset_bank(data, reg);
 
 	mutex_unlock(&data->lock);
-
 	return res;
 }
 
@@ -401,7 +398,6 @@ static int w83627ehf_write_value(struct w83627ehf_data *data, u16 reg,
 		       data->addr + ADDR_REG_OFFSET);
 	}
 	outb_p(value & 0xff, data->addr + DATA_REG_OFFSET);
-	w83627ehf_reset_bank(data, reg);
 
 	mutex_unlock(&data->lock);
 	return 0;
-- 
1.7.3.1





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