[PATCH v2] iio: adc: ade9000: fix NULL pointer dereference in clkout registration

ade9000_setup_clkout() passes NULL as the register address when
registering a divider clock. During clock registration, the common
clock framework calls clk_divider_recalc_rate(), which dereferences
the address through readl(). As a result, probing an ADE9000 configured
as a clock provider with an external input clock crashes.

CLKOUT passes CLKIN through without changing its rate. Register it as
a 1:1 fixed-factor clock, which does not require register access.

This change does not affect the configuration using the internal clock,
for which the driver does not register a clock provider.

Fixes: 81de7b4619fc ("iio: adc: add ade9000 support")
Cc: [email protected]
Signed-off-by: Linmao Li <[email protected]>
---
Changes in v2:
- Clarify that the configuration using the internal clock is unaffected.

 drivers/iio/adc/ade9000.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/ade9000.c b/drivers/iio/adc/ade9000.c
index e57e24b6acdf7..4e96cc37fbedf 100644
--- a/drivers/iio/adc/ade9000.c
+++ b/drivers/iio/adc/ade9000.c
@@ -1647,8 +1647,9 @@ static int ade9000_setup_clkout(struct device *dev, struct ade9000_state *st)
 		return 0;
 
 	/* CLKOUT passes through CLKIN with divider of 1 */
-	clkout_hw = devm_clk_hw_register_divider(dev, "clkout", __clk_get_name(st->clkin),
-						 CLK_SET_RATE_PARENT, NULL, 0, 1, 0, NULL);
+	clkout_hw = devm_clk_hw_register_fixed_factor(dev, "clkout",
+						      __clk_get_name(st->clkin),
+						      CLK_SET_RATE_PARENT, 1, 1);
 	if (IS_ERR(clkout_hw))
 		return dev_err_probe(dev, PTR_ERR(clkout_hw), "Failed to register clkout");
 

base-commit: 6b9f23b5460818aaf199dda90210d5fc08d66c8f
-- 
2.25.1