usb/isp1760: Allow to optionally trigger low-level chip reset via GPIOLIB.

Properly triggering the reset wire is necessary with the ISP1761 used
on Terasic DE4 Altera-FPGA boards using a NIOS2 processor, for example.

This is an optional implementation for the OF binding only. The other
bindings just pass an invalid GPIO to the isp1760_register() routine.

Example, usage in DTS:
        gpios = <&pio_isp1761rst_0 0 1>;
to point to a GPIO controller from within the ISP1761 node: GPIO 0, active low.
Signed-off-by: Joachim Foerster <joachim.foerster@missinglinkelectronics.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/isp1760-hcd.c

@@ -24,6 +24,7 @@
 #include <linux/timer.h>
 #include <asm/unaligned.h>
 #include <asm/cacheflush.h>
+#include <linux/gpio.h>
 
 #include "isp1760-hcd.h"
 
@@ -48,6 +49,8 @@ struct isp1760_hcd {
 	unsigned long		reset_done;
 	unsigned long		next_statechange;
 	unsigned int		devflags;
+
+	int			rst_gpio;
 };
 
 static inline struct isp1760_hcd *hcd_to_priv(struct usb_hcd *hcd)
@@ -433,6 +436,18 @@ static int isp1760_hc_setup(struct usb_hcd *hcd)
 	int result;
 	u32 scratch, hwmode;
 
+	/* low-level chip reset */
+	if (gpio_is_valid(priv->rst_gpio)) {
+		unsigned int rst_lvl;
+
+		rst_lvl = (priv->devflags &
+			   ISP1760_FLAG_RESET_ACTIVE_HIGH) ? 1 : 0;
+
+		gpio_set_value(priv->rst_gpio, rst_lvl);
+		mdelay(50);
+		gpio_set_value(priv->rst_gpio, !rst_lvl);
+	}
+
 	/* Setup HW Mode Control: This assumes a level active-low interrupt */
 	hwmode = HW_DATA_BUS_32BIT;
 
@@ -2207,6 +2222,7 @@ void deinit_kmem_cache(void)
 
 struct usb_hcd *isp1760_register(phys_addr_t res_start, resource_size_t res_len,
 				 int irq, unsigned long irqflags,
+				 int rst_gpio,
 				 struct device *dev, const char *busname,
 				 unsigned int devflags)
 {
@@ -2226,6 +2242,7 @@ struct usb_hcd *isp1760_register(phys_addr_t res_start, resource_size_t res_len,
 
 	priv = hcd_to_priv(hcd);
 	priv->devflags = devflags;
+	priv->rst_gpio = rst_gpio;
 	init_memory(priv);
 	hcd->regs = ioremap(res_start, res_len);
 	if (!hcd->regs) {

drivers/usb/host/isp1760-hcd.h

@@ -4,6 +4,7 @@
 /* exports for if */
 struct usb_hcd *isp1760_register(phys_addr_t res_start, resource_size_t res_len,
 				 int irq, unsigned long irqflags,
+				 int rst_gpio,
 				 struct device *dev, const char *busname,
 				 unsigned int devflags);
 int init_kmem_once(void);
@@ -126,6 +127,7 @@ typedef void (packet_enqueue)(struct usb_hcd *hcd, struct isp1760_qh *qh,
 #define ISP1760_FLAG_ISP1761		0x00000040 /* Chip is ISP1761 */
 #define ISP1760_FLAG_INTR_POL_HIGH	0x00000080 /* Interrupt polarity active high */
 #define ISP1760_FLAG_INTR_EDGE_TRIG	0x00000100 /* Interrupt edge triggered */
+#define ISP1760_FLAG_RESET_ACTIVE_HIGH	0x80000000 /* RESET GPIO active high */
 
 /* chip memory management */
 struct memory_chunk {

drivers/usb/host/isp1760-if.c

@@ -18,10 +18,12 @@
 #include "isp1760-hcd.h"
 
 #ifdef CONFIG_OF
+#include <linux/slab.h>
 #include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
+#include <linux/of_gpio.h>
 #endif
 
 #ifdef CONFIG_PCI
@@ -29,9 +31,14 @@
 #endif
 
 #ifdef CONFIG_OF
+struct isp1760 {
+	struct usb_hcd *hcd;
+	int rst_gpio;
+};
+
 static int of_isp1760_probe(struct platform_device *dev)
 {
-	struct usb_hcd *hcd;
+	struct isp1760 *drvdata;
 	struct device_node *dp = dev->dev.of_node;
 	struct resource *res;
 	struct resource memory;
@@ -41,6 +48,11 @@ static int of_isp1760_probe(struct platform_device *dev)
 	int ret;
 	const unsigned int *prop;
 	unsigned int devflags = 0;
+	enum of_gpio_flags gpio_flags;
+
+	drvdata = kzalloc(sizeof(*drvdata), GFP_KERNEL);
+	if (!drvdata)
+		return -ENOMEM;
 
 	ret = of_address_to_resource(dp, 0, &memory);
 	if (ret)
@@ -80,32 +92,57 @@ static int of_isp1760_probe(struct platform_device *dev)
 	if (of_get_property(dp, "dreq-polarity", NULL) != NULL)
 		devflags |= ISP1760_FLAG_DREQ_POL_HIGH;
 
-	hcd = isp1760_register(memory.start, res_len, virq,
-		IRQF_SHARED, &dev->dev, dev_name(&dev->dev),
+	drvdata->rst_gpio = of_get_gpio_flags(dp, 0, &gpio_flags);
+	if (gpio_is_valid(drvdata->rst_gpio)) {
+		ret = gpio_request(drvdata->rst_gpio, dev_name(&dev->dev));
+		if (!ret) {
+			if (!(gpio_flags & OF_GPIO_ACTIVE_LOW)) {
+				devflags |= ISP1760_FLAG_RESET_ACTIVE_HIGH;
+				gpio_direction_output(drvdata->rst_gpio, 0);
+			} else {
+				gpio_direction_output(drvdata->rst_gpio, 1);
+			}
+		} else {
+			drvdata->rst_gpio = ret;
+		}
+	}
+
+	drvdata->hcd = isp1760_register(memory.start, res_len, virq,
+					IRQF_SHARED, drvdata->rst_gpio,
+					&dev->dev, dev_name(&dev->dev),
 					devflags);
-	if (IS_ERR(hcd)) {
-		ret = PTR_ERR(hcd);
-		goto release_reg;
+	if (IS_ERR(drvdata->hcd)) {
+		ret = PTR_ERR(drvdata->hcd);
+		goto free_gpio;
 	}
 
-	dev_set_drvdata(&dev->dev, hcd);
+	dev_set_drvdata(&dev->dev, drvdata);
 	return ret;
 
+free_gpio:
+	if (gpio_is_valid(drvdata->rst_gpio))
+		gpio_free(drvdata->rst_gpio);
 release_reg:
 	release_mem_region(memory.start, res_len);
+	kfree(drvdata);
 	return ret;
 }
 
 static int of_isp1760_remove(struct platform_device *dev)
 {
-	struct usb_hcd *hcd = dev_get_drvdata(&dev->dev);
+	struct isp1760 *drvdata = dev_get_drvdata(&dev->dev);
 
 	dev_set_drvdata(&dev->dev, NULL);
 
-	usb_remove_hcd(hcd);
-	iounmap(hcd->regs);
-	release_mem_region(hcd->rsrc_start, hcd->rsrc_len);
-	usb_put_hcd(hcd);
+	usb_remove_hcd(drvdata->hcd);
+	iounmap(drvdata->hcd->regs);
+	release_mem_region(drvdata->hcd->rsrc_start, drvdata->hcd->rsrc_len);
+	usb_put_hcd(drvdata->hcd);
+
+	if (gpio_is_valid(drvdata->rst_gpio))
+		gpio_free(drvdata->rst_gpio);
+
+	kfree(drvdata);
 	return 0;
 }
 
@@ -242,7 +279,7 @@ static int __devinit isp1761_pci_probe(struct pci_dev *dev,
 
 	dev->dev.dma_mask = NULL;
 	hcd = isp1760_register(pci_mem_phy0, memlength, dev->irq,
-		IRQF_SHARED, &dev->dev, dev_name(&dev->dev),
+		IRQF_SHARED, -ENOENT, &dev->dev, dev_name(&dev->dev),
 		devflags);
 	if (IS_ERR(hcd)) {
 		ret_status = -ENODEV;
@@ -353,7 +390,8 @@ static int __devinit isp1760_plat_probe(struct platform_device *pdev)
 	}
 
 	hcd = isp1760_register(mem_res->start, mem_size, irq_res->start,
-			       irqflags, &pdev->dev, dev_name(&pdev->dev), devflags);
+			       irqflags, -ENOENT,
+			       &pdev->dev, dev_name(&pdev->dev), devflags);
 	if (IS_ERR(hcd)) {
 		pr_warning("isp1760: Failed to register the HCD device\n");
 		ret = -ENODEV;