crypto: sunxi-ss - Add optional reset control support

On sun6i and later platforms, the reset control is split out of the
clock gates. Add support for an optional reset control.

Signed-off-by: Chen-Yu Tsai <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

drivers/crypto/sunxi-ss/sun4i-ss-core.c

···
 #include <linux/scatterlist.h>
 #include <linux/interrupt.h>
 #include <linux/delay.h>
+#include <linux/reset.h>
 
 #include "sun4i-ss.h"
 
···
 	}
 	dev_dbg(&pdev->dev, "clock ahb_ss acquired\n");
 
+	ss->reset = devm_reset_control_get_optional(&pdev->dev, "ahb");
+	if (IS_ERR(ss->reset)) {
+		if (PTR_ERR(ss->reset) == -EPROBE_DEFER)
+			return PTR_ERR(ss->reset);
+		dev_info(&pdev->dev, "no reset control found\n");
+		ss->reset = NULL;
+	}
+
 	/* Enable both clocks */
 	err = clk_prepare_enable(ss->busclk);
 	if (err != 0) {
···
 	if (err != 0) {
 		dev_err(&pdev->dev, "Cannot set clock rate to ssclk\n");
 		goto error_clk;
+	}
+
+	/* Deassert reset if we have a reset control */
+	if (ss->reset) {
+		err = reset_control_deassert(ss->reset);
+		if (err) {
+			dev_err(&pdev->dev, "Cannot deassert reset control\n");
+			goto error_clk;
+		}
 	}
 
 	/*
···
 			break;
 		}
 	}
+	if (ss->reset)
+		reset_control_assert(ss->reset);
 error_clk:
 	clk_disable_unprepare(ss->ssclk);
 error_ssclk:
···
 	}
 
 	writel(0, ss->base + SS_CTL);
+	if (ss->reset)
+		reset_control_assert(ss->reset);
 	clk_disable_unprepare(ss->busclk);
 	clk_disable_unprepare(ss->ssclk);
 	return 0;

drivers/crypto/sunxi-ss/sun4i-ss.h

···
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
+#include <linux/reset.h>
 #include <crypto/scatterwalk.h>
 #include <linux/scatterlist.h>
 #include <linux/interrupt.h>
···
 	int irq;
 	struct clk *busclk;
 	struct clk *ssclk;
+	struct reset_control *reset;
 	struct device *dev;
 	struct resource *res;
 	spinlock_t slock; /* control the use of the device */