Patchwork [U-Boot,V2,2/6] power: Explicitly select pmic device's bus

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Submitter Leela Krishna Amudala
Date Oct. 7, 2013, 7:26 a.m.
Message ID <1381130784-14752-3-git-send-email-l.krishna@samsung.com>
Download mbox | patch
Permalink /patch/280942/
State Changes Requested
Delegated to: Minkyu Kang
Headers show

Comments

Leela Krishna Amudala - Oct. 7, 2013, 7:26 a.m.
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@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Leela Krishna Amudala <l.krishna@samsung.com>
Reviewed-by: Doug Anderson <dianders@google.com>
---
 drivers/power/power_i2c.c |   62 +++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 57 insertions(+), 5 deletions(-)
Simon Glass - Oct. 8, 2013, 5:51 p.m.
On Mon, Oct 7, 2013 at 1:26 AM, Leela Krishna Amudala <l.krishna@samsung.com
> wrote:

> 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@chromium.org>
> Signed-off-by: Simon Glass <sjg@chromium.org>
> Signed-off-by: Leela Krishna Amudala <l.krishna@samsung.com>
> Reviewed-by: Doug Anderson <dianders@google.com>
>

Acked-by: Simon Glass <sjg@chromium.org>
Ɓukasz Majewski - Oct. 9, 2013, 5:50 a.m.
Hi Leela,

> 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@chromium.org>
> Signed-off-by: Simon Glass <sjg@chromium.org>
> Signed-off-by: Leela Krishna Amudala <l.krishna@samsung.com>
> Reviewed-by: Doug Anderson <dianders@google.com>

I'd love to see Heiko's ACK on this patch.

Patch

diff --git a/drivers/power/power_i2c.c b/drivers/power/power_i2c.c
index ac76870..3cafa4d 100644
--- a/drivers/power/power_i2c.c
+++ b/drivers/power/power_i2c.c
@@ -16,9 +16,45 @@ 
 #include <i2c.h>
 #include <compiler.h>
 
+static int pmic_select(struct pmic *p)
+{
+	int ret, old_bus;
+
+	old_bus = i2c_get_bus_num();
+	if (old_bus != p->bus) {
+		debug("%s: Select bus %d\n", __func__, p->bus);
+		ret = i2c_set_bus_num(p->bus);
+		if (ret) {
+			debug("%s: Cannot select pmic %s, err %d\n",
+			      __func__, p->name, ret);
+			return -1;
+		}
+	}
+
+	return old_bus;
+}
+
+static int pmic_deselect(int old_bus)
+{
+	int ret;
+
+	if (old_bus != i2c_get_bus_num()) {
+		ret = i2c_set_bus_num(old_bus);
+		debug("%s: Select bus %d\n", __func__, old_bus);
+		if (ret) {
+			debug("%s: Cannot restore i2c bus, err %d\n",
+			      __func__, ret);
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
 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 +88,33 @@  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);
+	if (old_bus < 0)
 		return -1;
 
-	return 0;
+	ret = i2c_write(pmic_i2c_addr, reg, 1, buf, pmic_i2c_tx_num);
+	pmic_deselect(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);
+	if (old_bus < 0)
 		return -1;
 
+	ret = i2c_read(pmic_i2c_addr, reg, 1, buf, pmic_i2c_tx_num);
+	pmic_deselect(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 +144,15 @@  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);
+	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_deselect(old_bus);
+	if (ret) {
 		printf("Can't find PMIC:%s\n", p->name);
 		return -1;
 	}