mfd: syscon: Use regmap max_register_is_0 as needed

syscon has always set the optional max_register configuration of
regmap to ensure the correct checks are in place. However, a recent
commit 0ec74ad3c157 ("regmap: rework ->max_register handling")
introduced explicit configuration in regmap framework for register
maps that is exactly 1 register, when max_register is pointing to a
valid register 0. This commit solved a previous limitation of regmap
framework.

Update syscon driver to consistent in regmap configuration for
all sizes of syscons by using this new capability by setting
max_register_is_0, when the max_register is valid and 0.

Signed-off-by: Nishanth Menon <nm@ti.com>
Link: https://lore.kernel.org/r/20240903184710.1552067-1-nm@ti.com
Signed-off-by: Lee Jones <lee@kernel.org>

diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
index 2ce15f6..3e1d699 100644 (file)
--- a/drivers/mfd/syscon.c
+++ b/drivers/mfd/syscon.c
@@ -108,6 +108,8 @@ static struct syscon *of_syscon_register(struct device_node *np, bool check_res)
        syscon_config.reg_stride = reg_io_width;
        syscon_config.val_bits = reg_io_width * 8;
        syscon_config.max_register = resource_size(&res) - reg_io_width;
+       if (!syscon_config.max_register)
+               syscon_config.max_register_is_0 = true;
 
        regmap = regmap_init_mmio(NULL, base, &syscon_config);
        kfree(syscon_config.name);
@@ -357,6 +359,9 @@ static int syscon_probe(struct platform_device *pdev)
                return -ENOMEM;
 
        syscon_config.max_register = resource_size(res) - 4;
+       if (!syscon_config.max_register)
+               syscon_config.max_register_is_0 = true;
+
        if (pdata)
                syscon_config.name = pdata->label;
        syscon->regmap = devm_regmap_init_mmio(dev, base, &syscon_config);