reset: socfpga: Update reset-socfpga to read the altr,modrst-offset property

In order for the Arria10 to be able to re-use the reset driver for SoCFPGA
Cyclone5/Arria5, we need to read the 'altr,modrst-offset' property from the
device tree entry. The 'altr,modrst-offset' property is the first register
into the reset manager that is used for bringing peripherals out of reset.

The driver assumes a modrst-offset of 0x10 in order to support legacy
Cyclone5/Arria5 hardware.

Signed-off-by: Dinh Nguyen <[e-mail]>

drivers/reset/reset-socfpga.c

···
 #include <linux/types.h>
 
 #define NR_BANKS		4
-#define OFFSET_MODRST		0x10
 
 struct socfpga_reset_data {
 	spinlock_t			lock;
 	void __iomem			*membase;
+	u32				modrst_offset;
 	struct reset_controller_dev	rcdev;
 };
 
···
 
 	spin_lock_irqsave(&data->lock, flags);
 
-	reg = readl(data->membase + OFFSET_MODRST + (bank * NR_BANKS));
-	writel(reg | BIT(offset), data->membase + OFFSET_MODRST +
+	reg = readl(data->membase + data->modrst_offset + (bank * NR_BANKS));
+	writel(reg | BIT(offset), data->membase + data->modrst_offset +
 				 (bank * NR_BANKS));
 	spin_unlock_irqrestore(&data->lock, flags);
 
···
 
 	spin_lock_irqsave(&data->lock, flags);
 
-	reg = readl(data->membase + OFFSET_MODRST + (bank * NR_BANKS));
-	writel(reg & ~BIT(offset), data->membase + OFFSET_MODRST +
+	reg = readl(data->membase + data->modrst_offset + (bank * NR_BANKS));
+	writel(reg & ~BIT(offset), data->membase + data->modrst_offset +
 				  (bank * NR_BANKS));
 
 	spin_unlock_irqrestore(&data->lock, flags);
···
 	int offset = id % BITS_PER_LONG;
 	u32 reg;
 
-	reg = readl(data->membase + OFFSET_MODRST + (bank * NR_BANKS));
+	reg = readl(data->membase + data->modrst_offset + (bank * NR_BANKS));
 
 	return !(reg & BIT(offset));
 }
···
 {
 	struct socfpga_reset_data *data;
 	struct resource *res;
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
 
 	/*
 	 * The binding was mainlined without the required property.
···
 	data->membase = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(data->membase))
 		return PTR_ERR(data->membase);
+
+	if (of_property_read_u32(np, "altr,modrst-offset", &data->modrst_offset)) {
+		dev_warn(dev, "missing altr,modrst-offset property, assuming 0x10!\n");
+		data->modrst_offset = 0x10;
+	}
 
 	spin_lock_init(&data->lock);