i2c: muxes: add i2c gpio multiplexer driver
Add an i2c mux driver providing access to i2c bus segments using a
hardware MUX sitting on a master bus and controlled through gpio pins.
E.G. something like:
---------- ---------- Bus segment 1 - - - - -
| | SCL/SDA | |-------------- | |
| |------------| |
| | | | Bus segment 2 | |
| Linux | GPIO 1..N | MUX |--------------- Devices
| |------------| | | |
| | | | Bus segment M
| | | |---------------| |
---------- ---------- - - - - -
SCL/SDA of the master I2C bus is multiplexed to bus segment 1..M
according to the settings of the GPIO pins 1..N.
Note commit log from kernel
commit 92ed1a76("i2c: Add generic I2C multiplexer using GPIO API")
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Tested-by: Peng Fan <peng.fan@nxp.com> (i.MX6QP-Sabreauto)
Cc: Heiko Schocher <hs@denx.de>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Simon Glass <sjg@chromium.org>
diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
index 48900ed..156380c 100644
--- a/drivers/i2c/muxes/Kconfig
+++ b/drivers/i2c/muxes/Kconfig
@@ -34,3 +34,12 @@
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.
+
+config I2C_MUX_GPIO
+ tristate "GPIO-based I2C multiplexer"
+ depends on I2C_MUX && DM_GPIO
+ help
+ If you say yes to this option, support will be included for
+ a GPIO based I2C multiplexer. This driver provides access to
+ I2C busses connected through a MUX, which is controlled
+ through GPIO pins.
diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile
index 0811add..3831f4e 100644
--- a/drivers/i2c/muxes/Makefile
+++ b/drivers/i2c/muxes/Makefile
@@ -6,3 +6,4 @@
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
+obj-$(CONFIG_I2C_MUX_GPIO) += i2c-mux-gpio.o
diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c
new file mode 100644
index 0000000..0269b3a
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-gpio.c
@@ -0,0 +1,138 @@
+/*
+ * I2C multiplexer using GPIO API
+ *
+ * Copyright 2017 NXP
+ *
+ * Peng Fan <peng.fan@nxp.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <asm/io.h>
+#include <asm-generic/gpio.h>
+#include <common.h>
+#include <dm.h>
+#include <dm/pinctrl.h>
+#include <fdtdec.h>
+#include <i2c.h>
+#include <linux/errno.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/**
+ * struct i2c_mux_gpio_priv - private data for i2c mux gpio
+ *
+ * @values: the reg value of each child node
+ * @n_values: num of regs
+ * @gpios: the mux-gpios array
+ * @n_gpios: num of gpios in mux-gpios
+ * @idle: the value of idle-state
+ */
+struct i2c_mux_gpio_priv {
+ u32 *values;
+ int n_values;
+ struct gpio_desc *gpios;
+ int n_gpios;
+ u32 idle;
+};
+
+
+static int i2c_mux_gpio_select(struct udevice *dev, struct udevice *bus,
+ uint channel)
+{
+ struct i2c_mux_gpio_priv *priv = dev_get_priv(dev);
+ int i, ret;
+
+ for (i = 0; i < priv->n_gpios; i++) {
+ ret = dm_gpio_set_value(&priv->gpios[i], (channel >> i) & 1);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+static int i2c_mux_gpio_deselect(struct udevice *dev, struct udevice *bus,
+ uint channel)
+{
+ struct i2c_mux_gpio_priv *priv = dev_get_priv(dev);
+ int i, ret;
+
+ for (i = 0; i < priv->n_gpios; i++) {
+ ret = dm_gpio_set_value(&priv->gpios[i], (priv->idle >> i) & 1);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+static int i2c_mux_gpio_probe(struct udevice *dev)
+{
+ const void *fdt = gd->fdt_blob;
+ int node = dev_of_offset(dev);
+ struct i2c_mux_gpio_priv *mux = dev_get_priv(dev);
+ struct gpio_desc *gpios;
+ u32 *values;
+ int i = 0, subnode, ret;
+
+ mux->n_values = fdtdec_get_child_count(fdt, node);
+ values = devm_kzalloc(dev, sizeof(*mux->values) * mux->n_values,
+ GFP_KERNEL);
+ if (!values) {
+ dev_err(dev, "Cannot alloc values array");
+ return -ENOMEM;
+ }
+
+ fdt_for_each_subnode(subnode, fdt, node) {
+ *(values + i) = fdtdec_get_uint(fdt, subnode, "reg", -1);
+ i++;
+ }
+
+ mux->values = values;
+
+ mux->idle = fdtdec_get_uint(fdt, node, "idle-state", -1);
+
+ mux->n_gpios = gpio_get_list_count(dev, "mux-gpios");
+ if (mux->n_gpios < 0) {
+ dev_err(dev, "Missing mux-gpios property\n");
+ return -EINVAL;
+ }
+
+ gpios = devm_kzalloc(dev, sizeof(struct gpio_desc) * mux->n_gpios,
+ GFP_KERNEL);
+ if (!gpios) {
+ dev_err(dev, "Cannot allocate gpios array\n");
+ return -ENOMEM;
+ }
+
+ ret = gpio_request_list_by_name(dev, "mux-gpios", gpios, mux->n_gpios,
+ GPIOD_IS_OUT_ACTIVE);
+ if (ret <= 0) {
+ dev_err(dev, "Failed to request mux-gpios\n");
+ return ret;
+ }
+
+ mux->gpios = gpios;
+
+ return 0;
+}
+
+static const struct i2c_mux_ops i2c_mux_gpio_ops = {
+ .select = i2c_mux_gpio_select,
+ .deselect = i2c_mux_gpio_deselect,
+};
+
+static const struct udevice_id i2c_mux_gpio_ids[] = {
+ { .compatible = "i2c-mux-gpio", },
+ {}
+};
+
+U_BOOT_DRIVER(i2c_mux_gpio) = {
+ .name = "i2c_mux_gpio",
+ .id = UCLASS_I2C_MUX,
+ .of_match = i2c_mux_gpio_ids,
+ .ops = &i2c_mux_gpio_ops,
+ .probe = i2c_mux_gpio_probe,
+ .priv_auto_alloc_size = sizeof(struct i2c_mux_gpio_priv),
+};