[PATCH v2 4/6] net: phy: Port GPIO controlled MDIO multiplexer driver

[Andrey Smirnov]

Port Linux version driver to Barebox, to support such device found in
various revisions of ZII's VF610 development board.

Signed-off-by: Andrey Smirnov <andrew.smirnov at gmail.com>
---
 drivers/net/phy/Kconfig         |  10 +++
 drivers/net/phy/Makefile        |   1 +
 drivers/net/phy/mdio-mux-gpio.c | 147 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 158 insertions(+)
 create mode 100644 drivers/net/phy/mdio-mux-gpio.c

diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index 08ffd2d45..cda752b65 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -74,6 +74,16 @@ config MDIO_BUS_MUX
 	  to a parent bus.  Switching between child busses is done by
 	  device specific drivers.
 
+config MDIO_BUS_MUX_GPIO
+	bool "GPIO controlled MDIO bus multiplexers"
+	depends on OF_GPIO
+	select MDIO_BUS_MUX
+	help
+	  This module provides a driver for MDIO bus multiplexers that
+	  are controlled via GPIO lines.  The multiplexer connects one of
+	  several child MDIO busses to a parent bus.  Child bus
+	  selection is under the control of GPIO lines.
+
 endif
 
 endmenu
diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
index 89b4b80be..30b20f8ee 100644
--- a/drivers/net/phy/Makefile
+++ b/drivers/net/phy/Makefile
@@ -11,4 +11,5 @@ obj-$(CONFIG_MDIO_MVEBU)	+= mdio-mvebu.o
 obj-$(CONFIG_MDIO_BITBANG)	+= mdio-bitbang.o
 obj-$(CONFIG_MDIO_GPIO)		+= mdio-gpio.o
 obj-$(CONFIG_MDIO_BUS_MUX)	+= mdio-mux.o
+obj-$(CONFIG_MDIO_BUS_MUX_GPIO)	+= mdio-mux-gpio.o
 
diff --git a/drivers/net/phy/mdio-mux-gpio.c b/drivers/net/phy/mdio-mux-gpio.c
new file mode 100644
index 000000000..221353cbc
--- /dev/null
+++ b/drivers/net/phy/mdio-mux-gpio.c
@@ -0,0 +1,147 @@
+/*
+ * Copyright (c) 2017 Zodiac Inflight Innovation
+ * Author: Andrey Smirnov <andrew.smirnov at gmail.com>
+ *
+ * Based on analogous code from Linux kernel
+ *
+ * Copyright (C) 2011, 2012 Cavium, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 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.
+ *
+ */
+#include <common.h>
+#include <driver.h>
+#include <init.h>
+#include <linux/mdio-mux.h>
+#include <gpio.h>
+#include <of_gpio.h>
+
+
+struct mdio_mux_gpio_state {
+	struct gpio *gpios;
+	int gpios_num;
+};
+
+static void mdio_mux_gpio_set_active(struct mdio_mux_gpio_state *s,
+				     unsigned int mask, int value)
+{
+	while (mask) {
+		const int n = __ffs(mask);
+		mask >>= n + 1;
+
+		if (WARN_ON(n >= s->gpios_num))
+			break;
+
+		gpio_set_active(s->gpios[n].gpio, value);
+	}
+}
+
+static int mdio_mux_gpio_switch_fn(int current_child, int desired_child,
+				   void *data)
+{
+	if (current_child < 0)
+		current_child = 0;
+
+	if (current_child != desired_child) {
+		struct mdio_mux_gpio_state *s = data;
+		/*
+		 * GPIOs that are set in both current and desired
+		 * states can be left untouched. So we calculate them
+		 * and clear corresponding bits in both states.
+		 */
+		const int unchanged = current_child & desired_child;
+
+		current_child &= ~unchanged;
+		desired_child &= ~unchanged;
+
+		/*
+		 * First step: disable all of the currently selected
+		 * bits that are no loger needed
+		 */
+		mdio_mux_gpio_set_active(s, current_child, 0);
+		/*
+		 * Second step: enable all of the GPIOs that are
+		 * desired to be selected
+		 */
+		mdio_mux_gpio_set_active(s, desired_child, 1);
+	}
+
+	return 0;
+}
+
+static int mdio_mux_gpio_probe(struct device_d *dev)
+{
+	struct mdio_mux_gpio_state *s;
+	int i, r;
+
+	s = xzalloc(sizeof(*s));
+
+	s->gpios_num = of_gpio_count(dev->device_node);
+	if (s->gpios_num <= 0) {
+		dev_err(dev, "No GPIOs specified\n");
+		r = -EINVAL;
+		goto free_mem;
+	}
+
+	s->gpios = xzalloc(s->gpios_num * sizeof(s->gpios[0]));
+
+	for (i = 0; i < s->gpios_num; i++) {
+		enum of_gpio_flags flags;
+
+		r = of_get_gpio_flags(dev->device_node, i, &flags);
+		if (!gpio_is_valid(r)) {
+			r = (r < 0) ? r : -EINVAL;
+			goto free_mem;
+		}
+
+		s->gpios[i].gpio  = r;
+		s->gpios[i].label = dev_name(dev);
+		s->gpios[i].flags = GPIOF_OUT_INIT_INACTIVE;
+
+		if (flags & OF_GPIO_ACTIVE_LOW)
+			s->gpios[i].flags |= GPIOF_ACTIVE_LOW;
+	}
+
+	r = gpio_request_array(s->gpios, s->gpios_num);
+	if (r < 0)
+		goto free_gpios;
+
+
+	r = mdio_mux_init(dev, dev->device_node,
+			  mdio_mux_gpio_switch_fn, s, NULL);
+	if (r < 0)
+		goto free_gpios;
+
+	return 0;
+
+free_gpios:
+	gpio_free_array(s->gpios, s->gpios_num);
+free_mem:
+	free(s->gpios);
+	free(s);
+	return r;
+}
+
+static const struct of_device_id mdio_mux_gpio_match[] = {
+	{
+		.compatible = "mdio-mux-gpio",
+	},
+	{},
+};
+
+static struct driver_d mdio_mux_gpio_driver = {
+	.name	       = "mdio-mux-gpio",
+	.probe         = mdio_mux_gpio_probe,
+	.of_compatible = mdio_mux_gpio_match,
+};
+device_platform_driver(mdio_mux_gpio_driver);
-- 
2.14.3