regulator: s5m8767: fix get_register() error handling

The s5m8767_pmic_probe() function calls s5m8767_get_register() to
read data without checking the return code, which produces a compile-time
warning when that data is accessed:

drivers/regulator/s5m8767.c: In function 's5m8767_pmic_probe':
drivers/regulator/s5m8767.c:924:7: error: 'enable_reg' may be used uninitialized in this function [-Werror=maybe-uninitialized]
drivers/regulator/s5m8767.c:944:30: error: 'enable_val' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This changes the s5m8767_get_register() function to return a -EINVAL
not just for an invalid register number but also for an invalid
regulator number, as both would result in returning uninitialized
data. The s5m8767_pmic_probe() function is then changed accordingly
to fail on a read error, as all the other callers of s5m8767_get_register()
already do.

In practice this probably cannot happen, as we don't call
s5m8767_get_register() with invalid arguments, but the gcc
warning seems valid in principle, in terms writing safe
error checking.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 9c4c60554acf ("regulator: s5m8767: Convert to use regulator_[enable|disable|is_enabled]_regmap")
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 9 insertions, 4 deletions

diff --git a/drivers/regulator/s5m8767.c b/drivers/regulator/s5m8767.c
index 58f5d3b8e981..27343e1c43ef 100644
--- a/drivers/regulator/s5m8767.c
+++ b/drivers/regulator/s5m8767.c
@@ -202,9 +202,10 @@ static int s5m8767_get_register(struct s5m8767_info *s5m8767, int reg_id,
                 }
         }
 
-        if (i < s5m8767->num_regulators)
-                *enable_ctrl =
-                s5m8767_opmode_reg[reg_id][mode] << S5M8767_ENCTRL_SHIFT;
+        if (i >= s5m8767->num_regulators)
+                return -EINVAL;
+
+        *enable_ctrl = s5m8767_opmode_reg[reg_id][mode] << S5M8767_ENCTRL_SHIFT;
 
         return 0;
 }
@@ -937,8 +938,12 @@ static int s5m8767_pmic_probe(struct platform_device *pdev)
                         else
                                 regulators[id].vsel_mask = 0xff;
 
-                        s5m8767_get_register(s5m8767, id, &enable_reg,
+                        ret = s5m8767_get_register(s5m8767, id, &enable_reg,
                                              &enable_val);
+                        if (ret) {
+                                dev_err(s5m8767->dev, "error reading registers\n");
+                                return ret;
+                        }
                         regulators[id].enable_reg = enable_reg;
                         regulators[id].enable_mask = S5M8767_ENCTRL_MASK;
                         regulators[id].enable_val = enable_val;