[PATCH] Devicetree support for enc28j60 SPI Ethernet chip

[Michal Vanka]

Hi,
the following patch adds generic openfirmware/devicetree support to 
enc28j60 driver.

It also adds support for custom hardware based (FPGA) "interrupt line 
deasserter" for processors with level triggered interrupts
(for example Altera Nios2).

The interrupt line is deasserted by writing 1 to some output register
in the address space (this address is configured also through
devicetree).

Note: The interrupt line in enc28j60 chip can be deasserted by software
by clearing bit INTIE in the EIE register.
However this can't be done in interrupt context as the write goes
through SPI bus.

The patch was tested on custom Altera Nios2 system.

Signed-off-by: Michal Vanka <mv at vanka.net>

diff -uprN 
a/Documentation/devicetree/bindings/net/microchip-enc28j60.txt 
b/Documentation/devicetree/bindings/net/microchip-enc28j60.txt
--- a/Documentation/devicetree/bindings/net/microchip-enc28j60.txt 
1969-12-31 19:00:00.000000000 -0500
+++ b/Documentation/devicetree/bindings/net/microchip-enc28j60.txt 
2011-10-14 13:46:58.000000000 -0400
@@ -0,0 +1,31 @@
+* Microchip enc28j60 Ethernet
+
+Required properties:
+- compatible : Should be "microchip,enc28j60"
+- interrupts : Should contain 1 interrupt.
+- reg : Should be 0
+
+Optional properties:
+- interrupt_deassert_reg : should contain address of additional (FPGA)
+  interrupt deassert hardware for processors with level triggered 
interrupts
+
+
+Example (for enc28j60 under opencores tinyspi controller):
+
+tiny_spi_1: spi at 0x2160 {
+	compatible = "opencores,tiny-spi-1.0", "opencores,tiny-spi-rtlsvn2";
+	reg = < 0x00002160 0x00000020 >;
+	interrupt-parent = < &cpu >;
+	interrupts = < 2 >;
+	clock-frequency = < 100000000 >;
+	baud-width = < 8 >;	/* BAUD_WIDTH type NUMBER */
+	gpios = < &spi1_cs 0 0 >;
+	ethernet: enc28j60 at 0 {
+		compatible = "microchip,enc28j60";
+		spi-max-frequency = < 20000000 >;
+		reg = < 0 >;
+		interrupts = < 4 >;
+		interrupt_deassert_reg = < 0x00003000 >;
+	};			
+}; //end spi at 0x2160 (tiny_spi_1)
+
diff -uprN a/drivers/net/ethernet/microchip/enc28j60.c 
b/drivers/net/ethernet/microchip/enc28j60.c
--- a/drivers/net/ethernet/microchip/enc28j60.c	2011-10-02 
07:31:43.000000000 -0400
+++ b/drivers/net/ethernet/microchip/enc28j60.c	2011-10-14 
13:54:15.000000000 -0400
@@ -32,7 +32,7 @@
  #include "enc28j60_hw.h"

  #define DRV_NAME	"enc28j60"
-#define DRV_VERSION	"1.01"
+#define DRV_VERSION	"1.02"

  #define SPI_OPLEN	1

@@ -73,6 +73,7 @@ struct enc28j60_net {
  	int rxfilter;
  	u32 msg_enable;
  	u8 spi_transfer_buf[SPI_TRANSFER_BUF_LEN];
+	u8 *interrupt_deassert_reg;
  };

  /* use ethtool to change the level for any given device */
@@ -1320,6 +1321,10 @@ static irqreturn_t enc28j60_irq(int irq,
  	 * Remember that we access enc28j60 registers through SPI bus
  	 * via spi_sync() call.
  	 */
+
+	if(priv->interrupt_deassert_reg)
+		writeb(1,priv->interrupt_deassert_reg);
+
  	schedule_work(&priv->irq_work);

  	return IRQ_HANDLED;
@@ -1541,6 +1546,36 @@ static const struct net_device_ops enc28
  	.ndo_validate_addr	= eth_validate_addr,
  };

+#ifdef CONFIG_OF
+#include <linux/of.h>
+#include <linux/ioport.h>
+#include <linux/io.h>
+
+static int __devinit enc28j60_of_probe(struct spi_device *spi,struct 
enc28j60_net *priv)
+{
+
+	u8 *reg;
+	const __be32 *prop;
+	int len;
+	
+	if (!of_device_is_available(spi->dev.of_node))
+		return -ENODEV;	
+
+	prop = of_get_property(spi->dev.of_node, "interrupt_deassert_reg", &len);
+	
+	if(prop && len>=sizeof(__be32))
+		reg = be32_to_cpup(prop);
+	else
+		return -ENODEV;
+
+	if(!devm_request_mem_region(&spi->dev, reg, 4, DRV_NAME))
+		return -ENOMEM;
+
+	priv->interrupt_deassert_reg = devm_ioremap_nocache(&spi->dev, reg, 4);
+	return 0;	
+}
+#endif
+
  static int __devinit enc28j60_probe(struct spi_device *spi)
  {
  	struct net_device *dev;
@@ -1569,6 +1604,10 @@ static int __devinit enc28j60_probe(stru
  	INIT_WORK(&priv->restart_work, enc28j60_restart_work_handler);
  	dev_set_drvdata(&spi->dev, priv);	/* spi to priv reference */
  	SET_NETDEV_DEV(dev, &spi->dev);
+	priv->interrupt_deassert_reg = 0;
+#ifdef CONFIG_OF
+	enc28j60_of_probe(spi,priv);
+#endif	

  	if (!enc28j60_chipset_init(dev)) {
  		if (netif_msg_probe(priv))
@@ -1631,10 +1670,20 @@ static int __devexit enc28j60_remove(str
  	return 0;
  }

+#ifdef CONFIG_OF
+static const struct of_device_id enc28j60_dt_ids[] = {
+	{ .compatible = "microchip,enc28j60", },
+	{ /* sentinel */ }
+};
+#else
+#define enc28j60_dt_ids NULL
+#endif
+
  static struct spi_driver enc28j60_driver = {
  	.driver = {
  		   .name = DRV_NAME,
  		   .owner = THIS_MODULE,
+		   .of_match_table = enc28j60_dt_ids,
  	 },
  	.probe = enc28j60_probe,
  	.remove = __devexit_p(enc28j60_remove),