spi: bcm63xx-hsspi: add reset support

bcm63xx arch resets the HSSPI controller at early boot. However, bmips arch
needs to perform a reset when probing the driver.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20200616173235.3473149-3-noltari@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-bcm63xx-hsspi.c

@@ -20,6 +20,7 @@
 #include <linux/spi/spi.h>
 #include <linux/mutex.h>
 #include <linux/of.h>
+#include <linux/reset.h>
 
 #define HSSPI_GLOBAL_CTRL_REG			0x0
 #define GLOBAL_CTRL_CS_POLARITY_SHIFT		0
@@ -334,6 +335,7 @@ static int bcm63xx_hsspi_probe(struct platform_device *pdev)
 	struct clk *clk, *pll_clk = NULL;
 	int irq, ret;
 	u32 reg, rate, num_cs = HSSPI_SPI_MAX_CS;
+	struct reset_control *reset;
 
 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0)
@@ -348,10 +350,20 @@ static int bcm63xx_hsspi_probe(struct platform_device *pdev)
 	if (IS_ERR(clk))
 		return PTR_ERR(clk);
 
+	reset = devm_reset_control_get_optional_exclusive(dev, NULL);
+	if (IS_ERR(reset))
+		return PTR_ERR(reset);
+
 	ret = clk_prepare_enable(clk);
 	if (ret)
 		return ret;
 
+	ret = reset_control_reset(reset);
+	if (ret) {
+		dev_err(dev, "unable to reset device: %d\n", ret);
+		goto out_disable_clk;
+	}
+
 	rate = clk_get_rate(clk);
 	if (!rate) {
 		pll_clk = devm_clk_get(dev, "pll");