pwm: sti: It's now valid for number of PWM channels to be zero

Setting up the STI PWM IP as capture only, with zero PWM output devices
is a perfectly valid configuration. It is no longer okay to assume that
there must be at least 1 PWM output device. In this patch we make the
default number of PWM output devices zero and only configure channels
explicitly requested.

Reported-by: Peter Griffin <peter.griffin@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

1 files changed, 14 insertions, 1 deletions

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index 95014f57a9c6..9a1ca1986c30 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -483,6 +483,11 @@ static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
         if (!ret)
                 cdata->cpt_num_devs = num_devs;
 
+        if (!cdata->pwm_num_devs && !cdata->cpt_num_devs) {
+                dev_err(dev, "No channels configured\n");
+                return -EINVAL;
+        }
+
         reg_fields = cdata->reg_fields;
 
         pc->prescale_low = devm_regmap_field_alloc(dev, pc->regmap,
@@ -573,7 +578,7 @@ static int sti_pwm_probe(struct platform_device *pdev)
         cdata->reg_fields   = &sti_pwm_regfields[0];
         cdata->max_prescale = 0xff;
         cdata->max_pwm_cnt  = 255;
-        cdata->pwm_num_devs = 1;
+        cdata->pwm_num_devs = 0;
         cdata->cpt_num_devs = 0;
 
         pc->cdata = cdata;
@@ -585,6 +590,9 @@ static int sti_pwm_probe(struct platform_device *pdev)
         if (ret)
                 return ret;
 
+        if (!cdata->pwm_num_devs)
+                goto skip_pwm;
+
         pc->pwm_clk = of_clk_get_by_name(dev->of_node, "pwm");
         if (IS_ERR(pc->pwm_clk)) {
                 dev_err(dev, "failed to get PWM clock\n");
@@ -597,6 +605,10 @@ static int sti_pwm_probe(struct platform_device *pdev)
                 return ret;
         }
 
+skip_pwm:
+        if (!cdata->cpt_num_devs)
+                goto skip_cpt;
+
         pc->cpt_clk = of_clk_get_by_name(dev->of_node, "capture");
         if (IS_ERR(pc->cpt_clk)) {
                 dev_err(dev, "failed to get PWM capture clock\n");
@@ -609,6 +621,7 @@ static int sti_pwm_probe(struct platform_device *pdev)
                 return ret;
         }
 
+skip_cpt:
         pc->chip.dev = dev;
         pc->chip.ops = &sti_pwm_ops;
         pc->chip.base = -1;