Simple syscon devices may require deassertion of a reset signal in order
to access their register set. Rather than requiring a custom driver to
implement this, we can use the generic "resets" specifiers to link a
reset line to the syscon.
This change adds an optional reset line to the syscon device
description, and code to perform the deassertion/assertion on
probe/remove.
Signed-off-by: Jeremy Kerr <jk@xxxxxxxxxxxxxxxxxxxx>
---
drivers/mfd/syscon.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
index bdb2ce7ff03b..a0483dbfe17a 100644
--- a/drivers/mfd/syscon.c
+++ b/drivers/mfd/syscon.c
@@ -20,6 +20,7 @@
#include <linux/platform_data/syscon.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
+#include <linux/reset.h>
#include <linux/mfd/syscon.h>
#include <linux/slab.h>
@@ -31,6 +32,7 @@ static LIST_HEAD(syscon_list);
struct syscon {
struct device_node *np;
struct regmap *regmap;
+ struct reset_control *reset;
struct list_head list;
};
@@ -280,6 +282,7 @@ static int syscon_probe(struct platform_device *pdev)
struct regmap_config syscon_config = syscon_regmap_config;
struct resource *res;
void __iomem *base;
+ int rc;
syscon = devm_kzalloc(dev, sizeof(*syscon), GFP_KERNEL);
if (!syscon)
@@ -302,13 +305,32 @@ static int syscon_probe(struct platform_device *pdev)
return PTR_ERR(syscon->regmap);
}
+ syscon->reset = devm_reset_control_get_optional_exclusive(&pdev->dev,
+ "reset");
+ if (IS_ERR(syscon->reset))
+ return PTR_ERR(syscon->reset);
+
platform_set_drvdata(pdev, syscon);
+ rc = reset_control_deassert(syscon->reset);
+ if (rc) {
+ dev_err(dev, "failed to deassert reset line! rc: %d\n", rc);
+ return rc;
+ }
+
dev_dbg(dev, "regmap %pR registered\n", res);
return 0;
}
+static int syscon_remove(struct platform_device *pdev)
+{
+ struct syscon *syscon = platform_get_drvdata(pdev);
+
+ reset_control_assert(syscon->reset);
+ return 0;
+}
+
static const struct platform_device_id syscon_ids[] = {
{ "syscon", },
{ }
@@ -319,6 +341,7 @@ static struct platform_driver syscon_driver = {
.name = "syscon",
},
.probe = syscon_probe,
+ .remove = syscon_remove,
.id_table = syscon_ids,
};
--
2.35.1
