[U-Boot] [PATCH V4 2/6] power: Explicitly select pmic device's bus

[Leela Krishna Amudala]

The current pmic i2c code assumes the current i2c bus is
the same as the pmic device's bus. There is nothing ensuring
that to be true. Therefore, select the proper bus before performing
a transaction.

Signed-off-by: Aaron Durbin <adurbin at chromium.org>
Signed-off-by: Simon Glass <sjg at chromium.org>
Signed-off-by: Leela Krishna Amudala <l.krishna at samsung.com>
Reviewed-by: Doug Anderson <dianders at google.com>
Acked-by: Simon Glass <sjg at chromium.org>
---
 drivers/power/power_i2c.c |   48 ++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 43 insertions(+), 5 deletions(-)

diff --git a/drivers/power/power_i2c.c b/drivers/power/power_i2c.c
index ac76870..e4986bb 100644
--- a/drivers/power/power_i2c.c
+++ b/drivers/power/power_i2c.c
@@ -16,9 +16,29 @@
 #include <i2c.h>
 #include <compiler.h>
 
+static int pmic_select(int bus)
+{
+	int ret, old_bus;
+
+	old_bus = i2c_get_bus_num();
+
+	if (old_bus == bus)
+		return old_bus;
+
+	debug("%s: Select bus %d\n", __func__, bus);
+	ret = i2c_set_bus_num(bus);
+	if (ret) {
+		debug("%s: Cannot select pmic, err %d\n", __func__, ret);
+		return -1;
+	}
+
+	return old_bus;
+}
+
 int pmic_reg_write(struct pmic *p, u32 reg, u32 val)
 {
 	unsigned char buf[4] = { 0 };
+	int ret, old_bus;
 
 	if (check_reg(p, reg))
 		return -1;
@@ -52,23 +72,34 @@ int pmic_reg_write(struct pmic *p, u32 reg, u32 val)
 		return -1;
 	}
 
-	if (i2c_write(pmic_i2c_addr, reg, 1, buf, pmic_i2c_tx_num))
+	old_bus = pmic_select(p->bus);
+	if (old_bus < 0)
 		return -1;
 
-	return 0;
+	ret = i2c_write(pmic_i2c_addr, reg, 1, buf, pmic_i2c_tx_num);
+	pmic_select(old_bus);
+
+	return ret;
 }
 
 int pmic_reg_read(struct pmic *p, u32 reg, u32 *val)
 {
 	unsigned char buf[4] = { 0 };
 	u32 ret_val = 0;
+	int ret, old_bus;
 
 	if (check_reg(p, reg))
 		return -1;
 
-	if (i2c_read(pmic_i2c_addr, reg, 1, buf, pmic_i2c_tx_num))
+	old_bus = pmic_select(p->bus);
+	if (old_bus < 0)
 		return -1;
 
+	ret = i2c_read(pmic_i2c_addr, reg, 1, buf, pmic_i2c_tx_num);
+	pmic_select(old_bus);
+	if (ret)
+		return ret;
+
 	switch (pmic_i2c_tx_num) {
 	case 3:
 		if (p->sensor_byte_order == PMIC_SENSOR_BYTE_ORDER_BIG)
@@ -98,9 +129,16 @@ int pmic_reg_read(struct pmic *p, u32 reg, u32 *val)
 
 int pmic_probe(struct pmic *p)
 {
-	i2c_set_bus_num(p->bus);
+	int ret, old_bus;
+
+	old_bus = pmic_select(p->bus);
+	if (old_bus < 0)
+		return -1;
+
 	debug("Bus: %d PMIC:%s probed!\n", p->bus, p->name);
-	if (i2c_probe(pmic_i2c_addr)) {
+	ret = i2c_probe(pmic_i2c_addr);
+	pmic_select(old_bus);
+	if (ret) {
 		printf("Can't find PMIC:%s\n", p->name);
 		return -1;
 	}
-- 
1.7.9.5