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. The endianness of such register can be specified in device
tree if used, or in platform data.
Signed-off-by: York Sun <[email protected]>
CC: Wolfram Sang <[email protected]>
CC: Paul Bolle <[email protected]>
CC: Peter Korsgaard <[email protected]>
CC: Alexander Sverdlin <[email protected]>
---
According to Alexander's feedback, readback is added. Different sizes
are supported. I stick with iowrite but adding an option to use iowrite
big endian in in case needed. Both big- and little-endian are tested.
Comments are updated.
Change log:
v3: Add support of both big- and little-endian register
Add readback after writing to register
Add no-read option. By default, readback is alowed.
Fix using chan_id transferred back from i2c-mux. It was mistakenly
used as an index. It is actually the data to be written.
v2: Update to GPLv2+ licence header
Use iowrite instead of direct dereference the pointer to write register
Add support of difference register size of 1/2/4 bytes
Remove i2c_put_adapter(parent) in probe fucntion
Replace multiple dev_info() with dev_dbg()
Add idle_in_use variable to gate using idle value
Add __iomem for register pointer
Move platform data header file to include/linux/platform_data/
.../devicetree/bindings/i2c/i2c-mux-reg.txt | 75 +++++
drivers/i2c/muxes/Kconfig | 11 +
drivers/i2c/muxes/Makefile | 1 +
drivers/i2c/muxes/i2c-mux-reg.c | 299 ++++++++++++++++++++
include/linux/platform_data/i2c-mux-reg.h | 44 +++
5 files changed, 430 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 include/linux/platform_data/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..6e3197f
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-mux-reg.txt
@@ -0,0 +1,75 @@
+Register-based I2C Bus Mux
+
+This binding describes an I2C bus multiplexer that uses a single register
+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. The size must be either 1, 2, or 4 bytes. If reg is omitted, the
+ resource of this device will be used.
+- little-endian: The existence indicates the register is in little endian.
+ If omitted, the endianness of the host will be used.
+- no-read: The existence indicates reading the register is not allowed.
+- 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. The size is to determine
+ * whether iowrite32, iowrite16, or iowrite8 will be used.
+ */
+ reg = <0x6028 0x4>;
+ little-endian; /* little endian register on PCIe */
+ 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 written using iowrite32 */
+ reg = <1>;
+ #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..1692aec
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-reg.c
@@ -0,0 +1,299 @@
+/*
+ * I2C multiplexer using a single register
+ *
+ * Copyright 2015 Freescale Semiconductor
+ * York Sun <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ */
+
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/platform_data/i2c-mux-reg.h>
+#include <linux/platform_device.h>
+#include <linux/slab.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_id)
+{
+ if (!mux->data.reg)
+ return -EINVAL;
+
+ switch (mux->data.reg_size) {
+ case 4:
+ if (mux->data.little_endian) {
+ iowrite32(chan_id, mux->data.reg);
+ if (!mux->data.no_read)
+ ioread32(mux->data.reg);
+ } else {
+ iowrite32be(chan_id, mux->data.reg);
+ if (!mux->data.no_read)
+ ioread32(mux->data.reg);
+ }
+ break;
+ case 2:
+ if (mux->data.little_endian) {
+ iowrite16(chan_id, mux->data.reg);
+ if (!mux->data.no_read)
+ ioread16(mux->data.reg);
+ } else {
+ iowrite16be(chan_id, mux->data.reg);
+ if (!mux->data.no_read)
+ ioread16be(mux->data.reg);
+ }
+ break;
+ case 1:
+ iowrite8(chan_id, mux->data.reg);
+ if (!mux->data.no_read)
+ ioread8(mux->data.reg);
+ break;
+ default:
+ pr_err("Invalid register size\n");
+ return -EINVAL;
+ }
+
+ 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;
+
+ if (mux->data.idle_in_use)
+ return i2c_mux_reg_set(mux, mux->data.idle);
+
+ return 0;
+}
+
+#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);
+ if (of_find_property(np, "little-endian", NULL)) {
+ mux->data.little_endian = true;
+ } else {
+#ifdef __LITTLE_ENDIAN__
+ mux->data.little_endian = true;
+#elif defined(__BIG_ENDIAN__)
+ mux->data.little_endian = false;
+#else
+#error Endianness not defined?
+#endif
+ }
+ if (of_find_property(np, "no-read", NULL))
+ mux->data.no_read = true;
+ else
+ mux->data.no_read = false;
+
+ 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_in_use = true;
+
+ /* map address from "reg" if exists */
+ if (of_address_to_resource(np, 0, &res)) {
+ mux->data.reg_size = resource_size(&res);
+ if (mux->data.reg_size > 4) {
+ dev_err(&pdev->dev, "Invalid address size\n");
+ return -EINVAL;
+ }
+ 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;
+ } else {
+ ret = i2c_mux_reg_probe_dt(mux, pdev);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "Error parsing 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_size = resource_size(res);
+ if (mux->data.reg_size > 4) {
+ dev_err(&pdev->dev, "Invalid resource size\n");
+ return -EINVAL;
+ }
+ 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_in_use) {
+ 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_dbg(&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_dbg(&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 <[email protected]>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:i2c-mux-reg");
diff --git a/include/linux/platform_data/i2c-mux-reg.h b/include/linux/platform_data/i2c-mux-reg.h
new file mode 100644
index 0000000..cf0cc1e
--- /dev/null
+++ b/include/linux/platform_data/i2c-mux-reg.h
@@ -0,0 +1,44 @@
+/*
+ * I2C multiplexer using a single register
+ *
+ * Copyright 2015 Freescale Semiconductor
+ * York Sun <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ */
+
+#ifndef __LINUX_PLATFORM_DATA_I2C_MUX_REG_H
+#define __LINUX_PLATFORM_DATA_I2C_MUX_REG_H
+
+/**
+ * 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
+ * @little_endian: Indicating if the register is in little endian
+ * @no_read: Reading the register is not allowed by hardware
+ * @classes: Optional I2C auto-detection classes
+ * @idle: Value to write to mux when idle
+ * @idle_in_use: indicate if idle value is in use
+ * @reg: Virtual address of the register to switch channel
+ * @reg_size: register size in bytes
+ */
+struct i2c_mux_reg_platform_data {
+ int parent;
+ int base_nr;
+ const unsigned int *values;
+ int n_values;
+ bool little_endian;
+ bool no_read;
+ const unsigned int *classes;
+ u32 idle;
+ bool idle_in_use;
+ void __iomem *reg;
+ resource_size_t reg_size;
+};
+
+#endif /* __LINUX_PLATFORM_DATA_I2C_MUX_REG_H */
--
1.7.9.5
Hi!
On 18/06/15 21:57, ext York Sun wrote:
> 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. The endianness of such register can be specified in device
> tree if used, or in platform data.
>
> Signed-off-by: York Sun <[email protected]>
> CC: Wolfram Sang <[email protected]>
> CC: Paul Bolle <[email protected]>
> CC: Peter Korsgaard <[email protected]>
> CC: Alexander Sverdlin <[email protected]>
I can think about external FPGA applications performing MUX function,
so the code looks useful to me.
Acked-by: Alexander Sverdlin <[email protected]>
> ---
> According to Alexander's feedback, readback is added. Different sizes
> are supported. I stick with iowrite but adding an option to use iowrite
> big endian in in case needed. Both big- and little-endian are tested.
> Comments are updated.
>
> Change log:
> v3: Add support of both big- and little-endian register
> Add readback after writing to register
> Add no-read option. By default, readback is alowed.
> Fix using chan_id transferred back from i2c-mux. It was mistakenly
> used as an index. It is actually the data to be written.
>
> v2: Update to GPLv2+ licence header
> Use iowrite instead of direct dereference the pointer to write register
> Add support of difference register size of 1/2/4 bytes
> Remove i2c_put_adapter(parent) in probe fucntion
> Replace multiple dev_info() with dev_dbg()
> Add idle_in_use variable to gate using idle value
> Add __iomem for register pointer
> Move platform data header file to include/linux/platform_data/
>
> .../devicetree/bindings/i2c/i2c-mux-reg.txt | 75 +++++
> drivers/i2c/muxes/Kconfig | 11 +
> drivers/i2c/muxes/Makefile | 1 +
> drivers/i2c/muxes/i2c-mux-reg.c | 299 ++++++++++++++++++++
> include/linux/platform_data/i2c-mux-reg.h | 44 +++
> 5 files changed, 430 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 include/linux/platform_data/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..6e3197f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i2c/i2c-mux-reg.txt
> @@ -0,0 +1,75 @@
> +Register-based I2C Bus Mux
> +
> +This binding describes an I2C bus multiplexer that uses a single register
> +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. The size must be either 1, 2, or 4 bytes. If reg is omitted, the
> + resource of this device will be used.
> +- little-endian: The existence indicates the register is in little endian.
> + If omitted, the endianness of the host will be used.
> +- no-read: The existence indicates reading the register is not allowed.
> +- 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. The size is to determine
> + * whether iowrite32, iowrite16, or iowrite8 will be used.
> + */
> + reg = <0x6028 0x4>;
> + little-endian; /* little endian register on PCIe */
> + 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 written using iowrite32 */
> + reg = <1>;
> + #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..1692aec
> --- /dev/null
> +++ b/drivers/i2c/muxes/i2c-mux-reg.c
> @@ -0,0 +1,299 @@
> +/*
> + * I2C multiplexer using a single register
> + *
> + * Copyright 2015 Freescale Semiconductor
> + * York Sun <[email protected]>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License as published by the
> + * Free Software Foundation; either version 2 of the License, or (at your
> + * option) any later version.
> + */
> +
> +#include <linux/i2c.h>
> +#include <linux/i2c-mux.h>
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of_address.h>
> +#include <linux/platform_data/i2c-mux-reg.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.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_id)
> +{
> + if (!mux->data.reg)
> + return -EINVAL;
> +
> + switch (mux->data.reg_size) {
> + case 4:
> + if (mux->data.little_endian) {
> + iowrite32(chan_id, mux->data.reg);
> + if (!mux->data.no_read)
> + ioread32(mux->data.reg);
> + } else {
> + iowrite32be(chan_id, mux->data.reg);
> + if (!mux->data.no_read)
> + ioread32(mux->data.reg);
> + }
> + break;
> + case 2:
> + if (mux->data.little_endian) {
> + iowrite16(chan_id, mux->data.reg);
> + if (!mux->data.no_read)
> + ioread16(mux->data.reg);
> + } else {
> + iowrite16be(chan_id, mux->data.reg);
> + if (!mux->data.no_read)
> + ioread16be(mux->data.reg);
> + }
> + break;
> + case 1:
> + iowrite8(chan_id, mux->data.reg);
> + if (!mux->data.no_read)
> + ioread8(mux->data.reg);
> + break;
> + default:
> + pr_err("Invalid register size\n");
> + return -EINVAL;
> + }
> +
> + 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;
> +
> + if (mux->data.idle_in_use)
> + return i2c_mux_reg_set(mux, mux->data.idle);
> +
> + return 0;
> +}
> +
> +#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);
> + if (of_find_property(np, "little-endian", NULL)) {
> + mux->data.little_endian = true;
> + } else {
> +#ifdef __LITTLE_ENDIAN__
> + mux->data.little_endian = true;
> +#elif defined(__BIG_ENDIAN__)
> + mux->data.little_endian = false;
> +#else
> +#error Endianness not defined?
> +#endif
> + }
> + if (of_find_property(np, "no-read", NULL))
> + mux->data.no_read = true;
> + else
> + mux->data.no_read = false;
> +
> + 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_in_use = true;
> +
> + /* map address from "reg" if exists */
> + if (of_address_to_resource(np, 0, &res)) {
> + mux->data.reg_size = resource_size(&res);
> + if (mux->data.reg_size > 4) {
> + dev_err(&pdev->dev, "Invalid address size\n");
> + return -EINVAL;
> + }
> + 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;
> + } else {
> + ret = i2c_mux_reg_probe_dt(mux, pdev);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "Error parsing 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_size = resource_size(res);
> + if (mux->data.reg_size > 4) {
> + dev_err(&pdev->dev, "Invalid resource size\n");
> + return -EINVAL;
> + }
> + 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_in_use) {
> + 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_dbg(&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_dbg(&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 <[email protected]>");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:i2c-mux-reg");
> diff --git a/include/linux/platform_data/i2c-mux-reg.h b/include/linux/platform_data/i2c-mux-reg.h
> new file mode 100644
> index 0000000..cf0cc1e
> --- /dev/null
> +++ b/include/linux/platform_data/i2c-mux-reg.h
> @@ -0,0 +1,44 @@
> +/*
> + * I2C multiplexer using a single register
> + *
> + * Copyright 2015 Freescale Semiconductor
> + * York Sun <[email protected]>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License as published by the
> + * Free Software Foundation; either version 2 of the License, or (at your
> + * option) any later version.
> + */
> +
> +#ifndef __LINUX_PLATFORM_DATA_I2C_MUX_REG_H
> +#define __LINUX_PLATFORM_DATA_I2C_MUX_REG_H
> +
> +/**
> + * 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
> + * @little_endian: Indicating if the register is in little endian
> + * @no_read: Reading the register is not allowed by hardware
> + * @classes: Optional I2C auto-detection classes
> + * @idle: Value to write to mux when idle
> + * @idle_in_use: indicate if idle value is in use
> + * @reg: Virtual address of the register to switch channel
> + * @reg_size: register size in bytes
> + */
> +struct i2c_mux_reg_platform_data {
> + int parent;
> + int base_nr;
> + const unsigned int *values;
> + int n_values;
> + bool little_endian;
> + bool no_read;
> + const unsigned int *classes;
> + u32 idle;
> + bool idle_in_use;
> + void __iomem *reg;
> + resource_size_t reg_size;
> +};
> +
> +#endif /* __LINUX_PLATFORM_DATA_I2C_MUX_REG_H */
--
Best regards,
Alexander Sverdlin.
On Thu, Jun 18, 2015 at 12:57:38PM -0700, York Sun wrote:
> 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. The endianness of such register can be specified in device
> tree if used, or in platform data.
>
> Signed-off-by: York Sun <[email protected]>
Thanks for this driver!
...
> +- no-read: The existence indicates reading the register is not allowed.
Given that we have "read-only" properties already, I'd prefer this one
to be "write-only".
> +For each i2c child node, an I2C child bus will be created. They will
> +be numbered based on their order in the device tree.
This is a Linux specific detail (which can be overridden by aliases), so
it should not be in this document, I'd say.
> 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.
Typo here. And keep the sorting, please.
> obj-$(CONFIG_I2C_MUX_GPIO) += i2c-mux-gpio.o
> +obj-$(CONFIG_I2C_MUX_REG) += i2c-mux-reg.o
Keep the sorting, please.
> 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
> + adapter = of_find_i2c_adapter_by_node(adapter_np);
> + if (!adapter) {
> + dev_err(&pdev->dev, "Cannot find parent bus\n");
I don't think we should print something when deferring.
> + 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);
> + if (of_find_property(np, "little-endian", NULL)) {
You should check for a "big-endian" property as well, no?
> + 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;
Ditto about printing when deferred probing.
> +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_dbg(&pdev->dev, "Removed\n");
No need for that debug. The driver core has debug output for that.
Thanks,
Wolfram
On 08/11/2015 08:39 AM, Wolfram Sang wrote:
> On Thu, Jun 18, 2015 at 12:57:38PM -0700, York Sun wrote:
>> 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. The endianness of such register can be specified in device
>> tree if used, or in platform data.
>>
>> Signed-off-by: York Sun <[email protected]>
>
> Thanks for this driver!
>
> ...
>
>> +- no-read: The existence indicates reading the register is not allowed.
>
> Given that we have "read-only" properties already, I'd prefer this one
> to be "write-only".
Sure. That's easy to fix.
>
>> +For each i2c child node, an I2C child bus will be created. They will
>> +be numbered based on their order in the device tree.
>
> This is a Linux specific detail (which can be overridden by aliases), so
> it should not be in this document, I'd say.
OK. I can remove it.
>
>> 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.
>
> Typo here. And keep the sorting, please.
Will fix.
>
>> obj-$(CONFIG_I2C_MUX_GPIO) += i2c-mux-gpio.o
>> +obj-$(CONFIG_I2C_MUX_REG) += i2c-mux-reg.o
>
> Keep the sorting, please.
>
>> obj-$(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
>
>> + adapter = of_find_i2c_adapter_by_node(adapter_np);
>> + if (!adapter) {
>> + dev_err(&pdev->dev, "Cannot find parent bus\n");
>
> I don't think we should print something when deferring.
OK.
>
>> + 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);
>> + if (of_find_property(np, "little-endian", NULL)) {
>
> You should check for a "big-endian" property as well, no?
I use the little-endian as an option to indicate the nature of litten-endian
register. It is default to big-endian if this property doesn't exist. I prefer
this way unless you strongly suggest to add both and throw out an error if
neither exists.
>
>> + 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;
>
> Ditto about printing when deferred probing.
OK.
>
>> +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_dbg(&pdev->dev, "Removed\n");
>
> No need for that debug. The driver core has debug output for that.
Will remove.
Thanks for reviewing. I will send a new version after testing.
York
> >> + if (of_find_property(np, "little-endian", NULL)) {
> >
> > You should check for a "big-endian" property as well, no?
>
> I use the little-endian as an option to indicate the nature of litten-endian
> register. It is default to big-endian if this property doesn't exist. I prefer
> this way unless you strongly suggest to add both and throw out an error if
> neither exists.
I'd think that "little-endian" or "big-endian" force a setting. If none
is present, we shall take the CPU endianess. Or am I overlooking
something?
Oh, and I forgot the biggest issue: I get build errors, because
__LITTLE_ENDIAN__ should be __LITTLE_ENDIAN. Is this a recent change or
why did it work for you?
Thanks for the quick response,
Wolfram
On 08/11/2015 09:16 AM, Wolfram Sang wrote:
>>>> + if (of_find_property(np, "little-endian", NULL)) {
>>>
>>> You should check for a "big-endian" property as well, no?
>>
>> I use the little-endian as an option to indicate the nature of litten-endian
>> register. It is default to big-endian if this property doesn't exist. I prefer
>> this way unless you strongly suggest to add both and throw out an error if
>> neither exists.
>
> I'd think that "little-endian" or "big-endian" force a setting. If none
> is present, we shall take the CPU endianess. Or am I overlooking
> something?
You are right. The current code checks for littel-endian property. If missing,
the CPU endianess is used. Do you prefer to check littlen-endian first, if
missing then big-endian, if both missing then use CPU endianess?
>
> Oh, and I forgot the biggest issue: I get build errors, because
> __LITTLE_ENDIAN__ should be __LITTLE_ENDIAN. Is this a recent change or
> why did it work for you?
>
I tested it on 4.0.4 kernel. I see a lot of reference of __LITTLE_ENDIAN__. I
will test the new patch on the latest kernel.
York
> > I'd think that "little-endian" or "big-endian" force a setting. If none
> > is present, we shall take the CPU endianess. Or am I overlooking
> > something?
>
> You are right. The current code checks for littel-endian property. If missing,
> the CPU endianess is used. Do you prefer to check littlen-endian first, if
> missing then big-endian, if both missing then use CPU endianess?
Yes. Do it like this.
On 08/11/2015 01:02 PM, Wolfram Sang wrote:
>>> I'd think that "little-endian" or "big-endian" force a setting. If none
>>> is present, we shall take the CPU endianess. Or am I overlooking
>>> something?
>>
>> You are right. The current code checks for littel-endian property. If missing,
>> the CPU endianess is used. Do you prefer to check littlen-endian first, if
>> missing then big-endian, if both missing then use CPU endianess?
>
> Yes. Do it like this.
>
OK. Will do.
Do I have to add myself to MAINTAINER file for this driver?
York
> Do I have to add myself to MAINTAINER file for this driver?
Do you want to maintain this driver?
On 08/11/2015 06:35 PM, Wolfram Sang wrote:
>
>> Do I have to add myself to MAINTAINER file for this driver?
>
> Do you want to maintain this driver?
>
I prefer not, if that is OK.
York
> >> Do I have to add myself to MAINTAINER file for this driver?
> >
> > Do you want to maintain this driver?
>
> I prefer not, if that is OK.
Not my most favourite answer, but yes, it is ok ;)