mfd: syscon: Add hardware spinlock support

Some system control registers need hardware spinlock to synchronize
between the multiple subsystems, so we should add hardware spinlock
support for syscon.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

2 files changed, 27 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/mfd/syscon.txt b/Documentation/devicetree/bindings/mfd/syscon.txt
index 8b92d4576c42..25d9e9c2fd53 100644
--- a/Documentation/devicetree/bindings/mfd/syscon.txt
+++ b/Documentation/devicetree/bindings/mfd/syscon.txt
@@ -16,9 +16,17 @@ Required properties:
 Optional property:
 - reg-io-width: the size (in bytes) of the IO accesses that should be
   performed on the device.
+- hwlocks: reference to a phandle of a hardware spinlock provider node.
 
 Examples:
 gpr: iomuxc-gpr@20e0000 {
         compatible = "fsl,imx6q-iomuxc-gpr", "syscon";
         reg = <0x020e0000 0x38>;
+        hwlocks = <&hwlock1 1>;
+};
+
+hwlock1: hwspinlock@40500000 {
+        ...
+        reg = <0x40500000 0x1000>;
+        #hwlock-cells = <1>;
 };
diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
index b93fe4c4957a..7eaa40bc703f 100644
--- a/drivers/mfd/syscon.c
+++ b/drivers/mfd/syscon.c
@@ -13,6 +13,7 @@
  */
 
 #include <linux/err.h>
+#include <linux/hwspinlock.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/list.h>
@@ -87,6 +88,24 @@ static struct syscon *of_syscon_register(struct device_node *np)
         if (ret)
                 reg_io_width = 4;
 
+        ret = of_hwspin_lock_get_id(np, 0);
+        if (ret > 0 || (IS_ENABLED(CONFIG_HWSPINLOCK) && ret == 0)) {
+                syscon_config.use_hwlock = true;
+                syscon_config.hwlock_id = ret;
+                syscon_config.hwlock_mode = HWLOCK_IRQSTATE;
+        } else if (ret < 0) {
+                switch (ret) {
+                case -ENOENT:
+                        /* Ignore missing hwlock, it's optional. */
+                        break;
+                default:
+                        pr_err("Failed to retrieve valid hwlock: %d\n", ret);
+                        /* fall-through */
+                case -EPROBE_DEFER:
+                        goto err_regmap;
+                }
+        }
+
         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;