netdev/of/phy: Add MDIO bus multiplexer driven by GPIO lines.

The GPIO pins select which sub bus is connected to the master.

Initially tested with an sn74cbtlv3253 switch device wired into the
MDIO bus.

Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 142 insertions, 0 deletions

diff --git a/drivers/net/phy/mdio-mux-gpio.c b/drivers/net/phy/mdio-mux-gpio.c
new file mode 100644
index 000000000000..e0cc4ef33dee
--- /dev/null
+++ b/drivers/net/phy/mdio-mux-gpio.c
@@ -0,0 +1,142 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2011, 2012 Cavium, Inc.
+ */
+
+#include <linux/platform_device.h>
+#include <linux/device.h>
+#include <linux/of_mdio.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/phy.h>
+#include <linux/mdio-mux.h>
+#include <linux/of_gpio.h>
+
+#define DRV_VERSION "1.0"
+#define DRV_DESCRIPTION "GPIO controlled MDIO bus multiplexer driver"
+
+#define MDIO_MUX_GPIO_MAX_BITS 8
+
+struct mdio_mux_gpio_state {
+	int gpio[MDIO_MUX_GPIO_MAX_BITS];
+	unsigned int num_gpios;
+	void *mux_handle;
+};
+
+static int mdio_mux_gpio_switch_fn(int current_child, int desired_child,
+				   void *data)
+{
+	int change;
+	unsigned int n;
+	struct mdio_mux_gpio_state *s = data;
+
+	if (current_child == desired_child)
+		return 0;
+
+	change = current_child == -1 ? -1 : current_child ^ desired_child;
+
+	for (n = 0; n < s->num_gpios; n++) {
+		if (change & 1)
+			gpio_set_value_cansleep(s->gpio[n],
+						(desired_child & 1) != 0);
+		change >>= 1;
+		desired_child >>= 1;
+	}
+
+	return 0;
+}
+
+static int __devinit mdio_mux_gpio_probe(struct platform_device *pdev)
+{
+	enum of_gpio_flags f;
+	struct mdio_mux_gpio_state *s;
+	unsigned int num_gpios;
+	unsigned int n;
+	int r;
+
+	if (!pdev->dev.of_node)
+		return -ENODEV;
+
+	num_gpios = of_gpio_count(pdev->dev.of_node);
+	if (num_gpios == 0 || num_gpios > MDIO_MUX_GPIO_MAX_BITS)
+		return -ENODEV;
+
+	s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
+	if (!s)
+		return -ENOMEM;
+
+	s->num_gpios = num_gpios;
+
+	for (n = 0; n < num_gpios; ) {
+		int gpio = of_get_gpio_flags(pdev->dev.of_node, n, &f);
+		if (gpio < 0) {
+			r = (gpio == -ENODEV) ? -EPROBE_DEFER : gpio;
+			goto err;
+		}
+		s->gpio[n] = gpio;
+
+		n++;
+
+		r = gpio_request(gpio, "mdio_mux_gpio");
+		if (r)
+			goto err;
+
+		r = gpio_direction_output(gpio, 0);
+		if (r)
+			goto err;
+	}
+
+	r = mdio_mux_init(&pdev->dev,
+			  mdio_mux_gpio_switch_fn, &s->mux_handle, s);
+
+	if (r == 0) {
+		pdev->dev.platform_data = s;
+		return 0;
+	}
+err:
+	while (n) {
+		n--;
+		gpio_free(s->gpio[n]);
+	}
+	devm_kfree(&pdev->dev, s);
+	return r;
+}
+
+static int __devexit mdio_mux_gpio_remove(struct platform_device *pdev)
+{
+	struct mdio_mux_gpio_state *s = pdev->dev.platform_data;
+	mdio_mux_uninit(s->mux_handle);
+	return 0;
+}
+
+static struct of_device_id mdio_mux_gpio_match[] = {
+	{
+		.compatible = "mdio-mux-gpio",
+	},
+	{
+		/* Legacy compatible property. */
+		.compatible = "cavium,mdio-mux-sn74cbtlv3253",
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, mdio_mux_gpio_match);
+
+static struct platform_driver mdio_mux_gpio_driver = {
+	.driver = {
+		.name		= "mdio-mux-gpio",
+		.owner		= THIS_MODULE,
+		.of_match_table = mdio_mux_gpio_match,
+	},
+	.probe		= mdio_mux_gpio_probe,
+	.remove		= __devexit_p(mdio_mux_gpio_remove),
+};
+
+module_platform_driver(mdio_mux_gpio_driver);
+
+MODULE_DESCRIPTION(DRV_DESCRIPTION);
+MODULE_VERSION(DRV_VERSION);
+MODULE_AUTHOR("David Daney");
+MODULE_LICENSE("GPL");