[PATCH v2 3/4] usb: dwc3: of-simple: Add support to get resets for the device

[Vivek Gautam]

Add support to get a list of resets available for the device.
These resets must be kept de-asserted until the device is
in use.

Cc: Felipe Balbi <ba...@kernel.org>
Cc: Philipp Zabel <p.za...@pengutronix.de>
Signed-off-by: Vivek Gautam <vivek.gau...@codeaurora.org>
---

Changes since v1:
 - Using new APIs for reset control array.
 - Using the *_get_exclusive() API.
 - Added reset_control_array_put() to error and driver removal path.

 drivers/usb/dwc3/dwc3-of-simple.c | 45 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/drivers/usb/dwc3/dwc3-of-simple.c 
b/drivers/usb/dwc3/dwc3-of-simple.c
index fe414e7a9c78..96786f5ede0b 100644
--- a/drivers/usb/dwc3/dwc3-of-simple.c
+++ b/drivers/usb/dwc3/dwc3-of-simple.c
@@ -29,13 +29,48 @@
 #include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/pm_runtime.h>
+#include <linux/reset.h>
 
 struct dwc3_of_simple {
        struct device           *dev;
        struct clk              **clks;
        int                     num_clocks;
+       int                     num_resets;
+       struct reset_control_array *resets;
 };
 
+static int dwc3_of_simple_reset_init(struct dwc3_of_simple *simple, int count)
+{
+       struct device           *dev = simple->dev;
+       int                     ret;
+
+       /* Not all platforms have resets, so don't return a failure */
+       if (count < 0)
+               return 0;
+
+       simple->num_resets = count;
+
+       simple->resets = devm_kcalloc(dev, count, sizeof(simple->resets),
+                                                       GFP_KERNEL);
+       if (!simple->resets)
+               return -ENOMEM;
+
+       ret = of_reset_control_array_get_exclusive(dev->of_node, count,
+                                                       simple->resets);
+       if (ret) {
+               dev_err(dev, "failed to get device resets\n");
+               return ret;
+       }
+
+       ret = reset_control_array_deassert(count, simple->resets);
+       if (ret) {
+               reset_control_array_put(count, simple->resets);
+               return ret;
+       }
+
+       return 0;
+}
+
 static int dwc3_of_simple_clk_init(struct dwc3_of_simple *simple, int count)
 {
        struct device           *dev = simple->dev;
@@ -100,6 +135,10 @@ static int dwc3_of_simple_probe(struct platform_device 
*pdev)
        if (ret)
                return ret;
 
+       ret = dwc3_of_simple_reset_init(simple, of_reset_control_get_count(np));
+       if (ret)
+               return ret;
+
        ret = of_platform_populate(np, NULL, NULL, dev);
        if (ret) {
                for (i = 0; i < simple->num_clocks; i++) {
@@ -107,6 +146,9 @@ static int dwc3_of_simple_probe(struct platform_device 
*pdev)
                        clk_put(simple->clks[i]);
                }
 
+               reset_control_array_assert(simple->num_resets, simple->resets);
+               reset_control_array_put(simple->num_resets, simple->resets);
+
                return ret;
        }
 
@@ -128,6 +170,9 @@ static int dwc3_of_simple_remove(struct platform_device 
*pdev)
                clk_put(simple->clks[i]);
        }
 
+       reset_control_array_assert(simple->num_resets, simple->resets);
+       reset_control_array_put(simple->num_resets, simple->resets);
+
        of_platform_depopulate(dev);
 
        pm_runtime_put_sync(dev);
-- 
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