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Message-ID: <1434475692-4611-1-git-send-email-yorksun@freescale.com>
Date: Tue, 16 Jun 2015 10:28:12 -0700
From: York Sun <yorksun@...escale.com>
To: <wsa@...-dreams.de>
CC: <linux-kernel@...r.kernel.org>, <linux-i2c@...r.kernel.org>,
York Sun <yorksun@...escale.com>,
Peter Korsgaard <peter.korsgaard@...co.com>
Subject: [PATCH] driver/i2c/mux: Add register based mux i2c-mux-reg
Based on i2c-mux-gpio driver, similarly the register based mux
switch from one bus to another by setting a single register.
The register can be on PCIe bus, local bus, or any memory-mapped
address.
Signed-off-by: York Sun <yorksun@...escale.com>
CC: Wolfram Sang <wsa@...-dreams.de>
CC: Peter Korsgaard <peter.korsgaard@...co.com>
---
.../devicetree/bindings/i2c/i2c-mux-reg.txt | 69 ++++++
drivers/i2c/muxes/Kconfig | 11 +
drivers/i2c/muxes/Makefile | 1 +
drivers/i2c/muxes/i2c-mux-reg.c | 239 ++++++++++++++++++++
drivers/i2c/muxes/i2c-mux-reg.h | 38 ++++
5 files changed, 358 insertions(+)
create mode 100644 Documentation/devicetree/bindings/i2c/i2c-mux-reg.txt
create mode 100644 drivers/i2c/muxes/i2c-mux-reg.c
create mode 100644 drivers/i2c/muxes/i2c-mux-reg.h
diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux-reg.txt b/Documentation/devicetree/bindings/i2c/i2c-mux-reg.txt
new file mode 100644
index 0000000..ad7cc4f
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-mux-reg.txt
@@ -0,0 +1,69 @@
+Register-based I2C Bus Mux
+
+This binding describes an I2C bus multiplexer that uses a single regsiter
+to route the I2C signals.
+
+Required properties:
+- compatible: i2c-mux-reg
+- i2c-parent: The phandle of the I2C bus that this multiplexer's master-side
+ port is connected to.
+* Standard I2C mux properties. See mux.txt in this directory.
+* I2C child bus nodes. See mux.txt in this directory.
+
+Optional properties:
+- reg: this pair of <offset size> specifies the register to control the mux.
+ The <offset size> depends on its parent node. It can be any memory-mapped
+ address. If omitted, the resource of this device will be used.
+- idle-state: value to set the muxer to when idle. When no value is
+ given, it defaults to the last value used.
+
+For each i2c child node, an I2C child bus will be created. They will
+be numbered based on their order in the device tree.
+
+Whenever an access is made to a device on a child bus, the value set
+in the revelant node's reg property will be output to the register.
+
+If an idle state is defined, using the idle-state (optional) property,
+whenever an access is not being made to a device on a child bus, the
+register will be set according to the idle value.
+
+If an idle state is not defined, the most recently used value will be
+left programmed into the register.
+
+Example of a mux on PCIe card, the host is a powerpc SoC (big endian):
+
+ i2c-mux {
+ /* the <offset size> depends on the address translation
+ * of the parent device. If omitted, device resource
+ * will be used instead.
+ */
+ reg = <0x6028 0x4>;
+ compatible = "i2c-mux-reg";
+ #address-cells = <1>;
+ #size-cells = <0>;
+ i2c-parent = <&i2c1>;
+ i2c@0 {
+ reg = <0>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ si5338: clock-generator@70 {
+ compatible = "silabs,si5338";
+ reg = <0x70>;
+ /* other stuff */
+ };
+ };
+
+ i2c@1 {
+ /* data is in little endian on pcie bus */
+ reg = <0x01000000>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ si5338: clock-generator@70 {
+ compatible = "silabs,si5338";
+ reg = <0x70>;
+ /* other stuff */
+ };
+ };
+ };
diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
index f6d313e..77c1257 100644
--- a/drivers/i2c/muxes/Kconfig
+++ b/drivers/i2c/muxes/Kconfig
@@ -29,6 +29,17 @@ config I2C_MUX_GPIO
This driver can also be built as a module. If so, the module
will be called i2c-mux-gpio.
+config I2C_MUX_REG
+ tristate "Register-based I2C multiplexer"
+ help
+ If you say yes to this option, support will be included for a
+ register based I2C multiplexer. This driver provides access to
+ I2C busses connected through a MUX, which is controlled
+ by a sinple register.
+
+ This driver can also be built as a module. If so, the module
+ will be called i2c-mux-reg.
+
config I2C_MUX_PCA9541
tristate "NXP PCA9541 I2C Master Selector"
help
diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile
index 465778b..bc517bb 100644
--- a/drivers/i2c/muxes/Makefile
+++ b/drivers/i2c/muxes/Makefile
@@ -4,6 +4,7 @@
obj-$(CONFIG_I2C_ARB_GPIO_CHALLENGE) += i2c-arb-gpio-challenge.o
obj-$(CONFIG_I2C_MUX_GPIO) += i2c-mux-gpio.o
+obj-$(CONFIG_I2C_MUX_REG) += i2c-mux-reg.o
obj-$(CONFIG_I2C_MUX_PCA9541) += i2c-mux-pca9541.o
obj-$(CONFIG_I2C_MUX_PCA954x) += i2c-mux-pca954x.o
obj-$(CONFIG_I2C_MUX_PINCTRL) += i2c-mux-pinctrl.o
diff --git a/drivers/i2c/muxes/i2c-mux-reg.c b/drivers/i2c/muxes/i2c-mux-reg.c
new file mode 100644
index 0000000..03ce858
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-reg.c
@@ -0,0 +1,239 @@
+/*
+ * I2C multiplexer using a single register
+ *
+ * Copyright 2015 Freescale Semiconductor
+ * York Sun <yorksun@...escale.com>
+ *
+ * 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.
+ */
+
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include "i2c-mux-reg.h"
+
+struct regmux {
+ struct i2c_adapter *parent;
+ struct i2c_adapter **adap; /* child busses */
+ struct i2c_mux_reg_platform_data data;
+};
+
+static int i2c_mux_reg_set(const struct regmux *mux, unsigned int chan)
+{
+ if (!mux->data.reg || chan < 0 || chan > mux->data.n_values)
+ return -EINVAL;
+
+ *mux->data.reg = mux->data.values[chan];
+
+ return 0;
+}
+
+static int i2c_mux_reg_select(struct i2c_adapter *adap, void *data,
+ unsigned int chan)
+{
+ struct regmux *mux = data;
+
+ return i2c_mux_reg_set(mux, chan);
+}
+
+static int i2c_mux_reg_deselect(struct i2c_adapter *adap, void *data,
+ unsigned int chan)
+{
+ struct regmux *mux = data;
+
+ return i2c_mux_reg_set(mux, mux->data.idle);
+}
+
+#ifdef CONFIG_OF
+static int i2c_mux_reg_probe_dt(struct regmux *mux,
+ struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct device_node *adapter_np, *child;
+ struct i2c_adapter *adapter;
+ struct resource res;
+ unsigned *values;
+ int i = 0;
+
+ if (!np)
+ return -ENODEV;
+
+ adapter_np = of_parse_phandle(np, "i2c-parent", 0);
+ if (!adapter_np) {
+ dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
+ return -ENODEV;
+ }
+ adapter = of_find_i2c_adapter_by_node(adapter_np);
+ if (!adapter) {
+ dev_err(&pdev->dev, "Cannot find parent bus\n");
+ return -EPROBE_DEFER;
+ }
+ mux->parent = adapter;
+ mux->data.parent = i2c_adapter_id(adapter);
+ put_device(&adapter->dev);
+
+ mux->data.n_values = of_get_child_count(np);
+
+ values = devm_kzalloc(&pdev->dev,
+ sizeof(*mux->data.values) * mux->data.n_values,
+ GFP_KERNEL);
+ if (!values) {
+ dev_err(&pdev->dev, "Cannot allocate values array");
+ return -ENOMEM;
+ }
+
+ for_each_child_of_node(np, child) {
+ of_property_read_u32(child, "reg", values + i);
+ i++;
+ }
+ mux->data.values = values;
+
+ if (of_property_read_u32(np, "idle-state", &mux->data.idle))
+ mux->data.idle = I2C_MUX_REG_NO_IDLE;
+
+ /* map address from "reg" if exists */
+ if (!of_address_to_resource(np, 0, &res)) {
+ mux->data.reg = devm_ioremap_resource(&pdev->dev, &res);
+ if (IS_ERR(mux->data.reg))
+ return PTR_ERR(mux->data.reg);
+ }
+
+ return 0;
+}
+#else
+static int i2c_mux_reg_probe_dt(struct gpiomux *mux,
+ struct platform_device *pdev)
+{
+ return 0;
+}
+#endif
+
+static int i2c_mux_reg_probe(struct platform_device *pdev)
+{
+ struct regmux *mux;
+ struct i2c_adapter *parent;
+ struct resource *res;
+ int (*deselect)(struct i2c_adapter *, void *, u32);
+ unsigned int initial_state, class;
+ int i, ret, nr;
+
+ mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
+ if (!mux)
+ return -ENOMEM;
+
+ platform_set_drvdata(pdev, mux);
+
+ if (dev_get_platdata(&pdev->dev)) {
+ memcpy(&mux->data, dev_get_platdata(&pdev->dev),
+ sizeof(mux->data));
+
+ parent = i2c_get_adapter(mux->data.parent);
+ if (!parent) {
+ dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
+ mux->data.parent);
+ return -EPROBE_DEFER;
+ }
+ mux->parent = parent;
+ i2c_put_adapter(parent);
+ } else {
+ ret = i2c_mux_reg_probe_dt(mux, pdev);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "Cannot locate device tree");
+ return ret;
+ }
+ }
+
+ if (!mux->data.reg) {
+ dev_info(&pdev->dev,
+ "Register not set, using platform resource\n");
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ mux->data.reg = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(mux->data.reg))
+ return PTR_ERR(mux->data.reg);
+ }
+
+ mux->adap = devm_kzalloc(&pdev->dev,
+ sizeof(*mux->adap) * mux->data.n_values,
+ GFP_KERNEL);
+ if (!mux->adap) {
+ dev_err(&pdev->dev, "Cannot allocate i2c_adapter structure");
+ return -ENOMEM;
+ }
+
+ if (mux->data.idle != I2C_MUX_REG_NO_IDLE) {
+ initial_state = mux->data.idle;
+ deselect = i2c_mux_reg_deselect;
+ } else {
+ initial_state = mux->data.values[0];
+ deselect = NULL;
+ }
+
+ for (i = 0; i < mux->data.n_values; i++) {
+ nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
+ class = mux->data.classes ? mux->data.classes[i] : 0;
+
+ mux->adap[i] = i2c_add_mux_adapter(mux->parent, &pdev->dev, mux,
+ nr, mux->data.values[i],
+ class, i2c_mux_reg_select,
+ deselect);
+ if (!mux->adap[i]) {
+ ret = -ENODEV;
+ dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
+ goto add_adapter_failed;
+ }
+ }
+
+ dev_info(&pdev->dev, "%d port mux on %s adapter\n",
+ mux->data.n_values, mux->parent->name);
+
+ return 0;
+
+add_adapter_failed:
+ for (; i > 0; i--)
+ i2c_del_mux_adapter(mux->adap[i - 1]);
+
+ return ret;
+}
+
+static int i2c_mux_reg_remove(struct platform_device *pdev)
+{
+ struct regmux *mux = platform_get_drvdata(pdev);
+ int i;
+
+ for (i = 0; i < mux->data.n_values; i++)
+ i2c_del_mux_adapter(mux->adap[i]);
+
+ i2c_put_adapter(mux->parent);
+
+ dev_info(&pdev->dev, "Removed\n");
+
+ return 0;
+}
+
+static const struct of_device_id i2c_mux_reg_of_match[] = {
+ { .compatible = "i2c-mux-reg", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, i2c_mux_reg_of_match);
+
+static struct platform_driver i2c_mux_reg_driver = {
+ .probe = i2c_mux_reg_probe,
+ .remove = i2c_mux_reg_remove,
+ .driver = {
+ .owner = THIS_MODULE,
+ .name = "i2c-mux-reg",
+ },
+};
+
+module_platform_driver(i2c_mux_reg_driver);
+
+MODULE_DESCRIPTION("Register-based I2C multiplexer driver");
+MODULE_AUTHOR("York Sun <yorksun@...escale.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:i2c-mux-reg");
diff --git a/drivers/i2c/muxes/i2c-mux-reg.h b/drivers/i2c/muxes/i2c-mux-reg.h
new file mode 100644
index 0000000..e213988
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-reg.h
@@ -0,0 +1,38 @@
+/*
+ * I2C multiplexer using a single register
+ *
+ * Copyright 2015 Freescale Semiconductor
+ * York Sun <yorksun@...escale.com>
+ *
+ * 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.
+ */
+
+#ifndef __LINUX_I2C_MUX_REG_H
+#define __LINUX_I2C_MUX_REG_H
+
+/* MUX has no specific idel mode */
+#define I2C_MUX_REG_NO_IDLE ((unsigned)-1)
+
+/**
+ * struct i2c_mux_reg_platform_data - Platform-dependent data for i2c-mux-reg
+ * @parent: Parent I2C bus adapter number
+ * @base_nr: Base I2C bus number to number adapters from or zero for dynamic
+ * @values: Array of value for each channel
+ * @n_values: Number of multiplexer channels
+ * @classes: Optional I2C auto-detection classes
+ * @idle: Value to write to mux when idle
+ * @reg: Virtual address of the register to switch channel
+ */
+struct i2c_mux_reg_platform_data {
+ int parent;
+ int base_nr;
+ const unsigned int *values;
+ int n_values;
+ const unsigned int *classes;
+ unsigned int idle;
+ unsigned int *reg;
+};
+
+#endif /* __LINUX_I2C_MUX_REG_H */
--
1.7.9.5
--
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