i2c: muxes: Add support for TI PCA954X mux

Add support for common TI i2c mux which is available on ZynqMP zcu102
board.
DM i2c mux core code is selecting/deselecting bus before/after
every command is performed that's why only one channel is active at a
time. That's also the reason why deselect is just disable all available
channels.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/i2c/muxes/Kconfig

@@ -24,3 +24,13 @@ config I2C_ARB_GPIO_CHALLENGE
 	  I2C multimaster arbitration scheme using GPIOs and a challenge &
 	  response mechanism where masters have to claim the bus by asserting
 	  a GPIO.
+
+config I2C_MUX_PCA954x
+	tristate "TI PCA954x I2C Mux/switches"
+	depends on I2C_MUX
+	help
+	  If you say yes here you get support for the TI PCA954x
+	  I2C mux/switch devices. It is x width I2C multiplexer which enables to
+	  paritioning I2C bus and connect multiple devices with the same address
+	  to the same I2C controller where driver handles proper routing to
+	  target i2c device. PCA9544 and PCA9548 are supported.

drivers/i2c/muxes/Makefile

@@ -5,3 +5,4 @@
 #
 obj-$(CONFIG_I2C_ARB_GPIO_CHALLENGE) += i2c-arb-gpio-challenge.o
 obj-$(CONFIG_$(SPL_)I2C_MUX) += i2c-mux-uclass.o
+obj-$(CONFIG_I2C_MUX_PCA954x) += pca954x.o

drivers/i2c/muxes/pca954x.c

@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2015 - 2016 Xilinx, Inc.
+ * Written by Michal Simek
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <i2c.h>
+#include <asm/gpio.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct pca954x_priv {
+	u32 addr; /* I2C mux address */
+	u32 width; /* I2C mux width - number of busses */
+};
+
+static int pca954x_deselect(struct udevice *mux, struct udevice *bus,
+			    uint channel)
+{
+	struct pca954x_priv *priv = dev_get_priv(mux);
+	uchar byte = 0;
+
+	return dm_i2c_write(mux, priv->addr, &byte, 1);
+}
+
+static int pca954x_select(struct udevice *mux, struct udevice *bus,
+			  uint channel)
+{
+	struct pca954x_priv *priv = dev_get_priv(mux);
+	uchar byte = 1 << channel;
+
+	return dm_i2c_write(mux, priv->addr, &byte, 1);
+}
+
+static const struct i2c_mux_ops pca954x_ops = {
+	.select = pca954x_select,
+	.deselect = pca954x_deselect,
+};
+
+static const struct udevice_id pca954x_ids[] = {
+	{ .compatible = "nxp,pca9548", .data = (ulong)8 },
+	{ .compatible = "nxp,pca9544", .data = (ulong)4 },
+	{ }
+};
+
+static int pca954x_ofdata_to_platdata(struct udevice *dev)
+{
+	struct pca954x_priv *priv = dev_get_priv(dev);
+
+	priv->addr = fdtdec_get_int(gd->fdt_blob, dev->of_offset, "reg", 0);
+	if (!priv->addr) {
+		debug("MUX not found\n");
+		return -ENODEV;
+	}
+	priv->width = dev_get_driver_data(dev);
+
+	if (!priv->width) {
+		debug("No I2C MUX width specified\n");
+		return -EINVAL;
+	}
+
+	debug("Device %s at 0x%x with width %d\n",
+	      dev->name, priv->addr, priv->width);
+
+	return 0;
+}
+
+U_BOOT_DRIVER(pca954x) = {
+	.name = "pca954x",
+	.id = UCLASS_I2C_MUX,
+	.of_match = pca954x_ids,
+	.ops = &pca954x_ops,
+	.ofdata_to_platdata = pca954x_ofdata_to_platdata,
+	.priv_auto_alloc_size = sizeof(struct pca954x_priv),
+};