[lvc-project] [PATCH 1/1] power: supply: twl4030_charger: check return values in twl4030_charger_enable_usb()

[Ivan Abramov]

twl4030_charger_enable_usb() ignores multiple return values from I2C
writes and helper calls. This can lead to silent failures where the
hardware is not configured correctly.

Add return value checks and error logging to fix it.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 7f4a633d2133 ("twl4030_charger: add software controlled linear charging mode.")
Fixes: e9f14c18b83c ("twl4030_charger: Change TWL4030_MODULE_* ids to TWL_MODULE_*")
Fixes: 2e727f1787e3 ("power_supply: Add driver for TWL4030/TPS65950 BCI charger")
Signed-off-by: Ivan Abramov <i.abramov at mt-integration.ru>
---
 drivers/power/supply/twl4030_charger.c | 69 +++++++++++++++++++++++++-
 1 file changed, 68 insertions(+), 1 deletion(-)

diff --git a/drivers/power/supply/twl4030_charger.c b/drivers/power/supply/twl4030_charger.c
index 04216b2bfb6c..a32e155c59f1 100644
--- a/drivers/power/supply/twl4030_charger.c
+++ b/drivers/power/supply/twl4030_charger.c
@@ -466,11 +466,24 @@ static int twl4030_charger_enable_usb(struct twl4030_bci *bci, bool enable)
 			}
 			/* forcing the field BCIAUTOUSB (BOOT_BCI[1]) to 1 */
 			ret = twl4030_clear_set_boot_bci(0, TWL4030_BCIAUTOUSB);
+			if (ret < 0) {
+				dev_err(bci->dev,
+					"failed to set BCIAUTOUSB: %d\n",
+					ret);
+				return ret;
+			}
+
 		}
 
 		/* forcing USBFASTMCHG(BCIMFSTS4[2]) to 1 */
 		ret = twl4030_clear_set(TWL_MODULE_MAIN_CHARGE, 0,
 			TWL4030_USBFASTMCHG, TWL4030_BCIMFSTS4);
+		if (ret < 0) {
+			dev_err(bci->dev,
+				"failed to set USBFASTMCHG: %d\n",
+				ret);
+			return ret;
+		}
 		if (bci->usb_mode == CHARGE_LINEAR) {
 			/* Enable interrupts now. */
 			reg = ~(u32)(TWL4030_ICHGLOW | TWL4030_TBATOR2 |
@@ -483,22 +496,58 @@ static int twl4030_charger_enable_usb(struct twl4030_bci *bci, bool enable)
 					ret);
 				return ret;
 			}
-			twl4030_clear_set_boot_bci(TWL4030_BCIAUTOAC|TWL4030_CVENAC, 0);
+			ret = twl4030_clear_set_boot_bci(TWL4030_BCIAUTOAC|TWL4030_CVENAC, 0);
+			if (ret < 0) {
+				dev_err(bci->dev,
+					"failed to clear AC flags: %d\n",
+					ret);
+				return ret;
+			}
 			/* Watch dog key: WOVF acknowledge */
 			ret = twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0x33,
 					       TWL4030_BCIWDKEY);
+			if (ret < 0) {
+				dev_err(bci->dev,
+					"failed to write BCIWDKEY (0x33): %d\n",
+					ret);
+				return ret;
+			}
 			/* 0x24 + EKEY6: off mode */
 			ret = twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0x2a,
 					       TWL4030_BCIMDKEY);
+			if (ret < 0) {
+				dev_err(bci->dev,
+					"failed to write BCIMDKEY (0x2a): %d\n",
+					ret);
+				return ret;
+			}
 			/* EKEY2: Linear charge: USB path */
 			ret = twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0x26,
 					       TWL4030_BCIMDKEY);
+			if (ret < 0) {
+				dev_err(bci->dev,
+					"failed to write BCIMDKEY (0x26): %d\n",
+					ret);
+				return ret;
+			}
 			/* WDKEY5: stop watchdog count */
 			ret = twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0xf3,
 					       TWL4030_BCIWDKEY);
+			if (ret < 0) {
+				dev_err(bci->dev,
+					"failed to write BCIWDKEY (0xf3): %d\n",
+					ret);
+				return ret;
+			}
 			/* enable MFEN3 access */
 			ret = twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0x9c,
 					       TWL4030_BCIMFKEY);
+			if (ret < 0) {
+				dev_err(bci->dev,
+					"failed to write BCIMFKEY: %d\n",
+					ret);
+				return ret;
+			}
 			 /* ICHGEOCEN - end-of-charge monitor (current < 80mA)
 			  *                      (charging continues)
 			  * ICHGLOWEN - current level monitor (charge continues)
@@ -506,11 +555,29 @@ static int twl4030_charger_enable_usb(struct twl4030_bci *bci, bool enable)
 			  */
 			ret = twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0xf0,
 					       TWL4030_BCIMFEN3);
+			if (ret < 0) {
+				dev_err(bci->dev,
+					"failed to write BCIMFEN3: %d\n",
+					ret);
+				return ret;
+			}
 		}
 	} else {
 		ret = twl4030_clear_set_boot_bci(TWL4030_BCIAUTOUSB, 0);
+		if (ret < 0) {
+			dev_err(bci->dev,
+				"failed to clear BCIAUTOUSB: %d\n",
+				ret);
+			return ret;
+		}
 		ret |= twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0x2a,
 					TWL4030_BCIMDKEY);
+		if (ret < 0) {
+			dev_err(bci->dev,
+				"failed to write BCIMDKEY: %d\n",
+				ret);
+			return ret;
+		}
 		if (bci->usb_enabled) {
 			pm_runtime_put_autosuspend(bci->transceiver->dev);
 			bci->usb_enabled = 0;
-- 
2.39.5