* 'i2c-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jdelvare/staging: i2c: Constify i2c_client where possible i2c-algo-bit: Complain about masters which can't read SCL i2c-algo-bit: Refactor adapter registration i2c: Add generic I2C multiplexer using GPIO API i2c-nforce2: Remove unnecessary cast of pci_get_drvdata i2c-i801: Include <linux/slab.h>tirimbino
Linus Torvalds
14 years ago
commit
8adbf8d467
@ -0,0 +1,65 @@ |
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Kernel driver gpio-i2cmux |
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|
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Author: Peter Korsgaard <peter.korsgaard@barco.com> |
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|
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Description |
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----------- |
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|
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gpio-i2cmux is an i2c mux driver providing access to I2C bus segments |
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from a master I2C bus and a hardware MUX controlled through GPIO pins. |
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|
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E.G.: |
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|
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---------- ---------- Bus segment 1 - - - - - |
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| | SCL/SDA | |-------------- | | |
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| |------------| | |
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| | | | Bus segment 2 | | |
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| Linux | GPIO 1..N | MUX |--------------- Devices |
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| |------------| | | | |
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| | | | Bus segment M |
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| | | |---------------| | |
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---------- ---------- - - - - - |
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|
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SCL/SDA of the master I2C bus is multiplexed to bus segment 1..M |
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according to the settings of the GPIO pins 1..N. |
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Usage |
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----- |
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gpio-i2cmux uses the platform bus, so you need to provide a struct |
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platform_device with the platform_data pointing to a struct |
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gpio_i2cmux_platform_data with the I2C adapter number of the master |
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bus, the number of bus segments to create and the GPIO pins used |
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to control it. See include/linux/gpio-i2cmux.h for details. |
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E.G. something like this for a MUX providing 4 bus segments |
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controlled through 3 GPIO pins: |
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#include <linux/gpio-i2cmux.h> |
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#include <linux/platform_device.h> |
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static const unsigned myboard_gpiomux_gpios[] = { |
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AT91_PIN_PC26, AT91_PIN_PC25, AT91_PIN_PC24 |
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}; |
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static const unsigned myboard_gpiomux_values[] = { |
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0, 1, 2, 3 |
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}; |
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static struct gpio_i2cmux_platform_data myboard_i2cmux_data = { |
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.parent = 1, |
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.base_nr = 2, /* optional */ |
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.values = myboard_gpiomux_values, |
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.n_values = ARRAY_SIZE(myboard_gpiomux_values), |
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.gpios = myboard_gpiomux_gpios, |
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.n_gpios = ARRAY_SIZE(myboard_gpiomux_gpios), |
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.idle = 4, /* optional */ |
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}; |
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|
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static struct platform_device myboard_i2cmux = { |
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.name = "gpio-i2cmux", |
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.id = 0, |
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.dev = { |
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.platform_data = &myboard_i2cmux_data, |
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}, |
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}; |
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@ -0,0 +1,184 @@ |
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/*
|
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* I2C multiplexer using GPIO API |
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* |
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* Peter Korsgaard <peter.korsgaard@barco.com> |
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* |
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* This program is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License version 2 as |
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* published by the Free Software Foundation. |
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*/ |
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#include <linux/i2c.h> |
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#include <linux/i2c-mux.h> |
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#include <linux/gpio-i2cmux.h> |
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#include <linux/platform_device.h> |
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#include <linux/init.h> |
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#include <linux/module.h> |
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#include <linux/slab.h> |
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#include <linux/gpio.h> |
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struct gpiomux { |
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struct i2c_adapter *parent; |
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struct i2c_adapter **adap; /* child busses */ |
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struct gpio_i2cmux_platform_data data; |
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}; |
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static void gpiomux_set(const struct gpiomux *mux, unsigned val) |
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{ |
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int i; |
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for (i = 0; i < mux->data.n_gpios; i++) |
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gpio_set_value(mux->data.gpios[i], val & (1 << i)); |
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} |
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static int gpiomux_select(struct i2c_adapter *adap, void *data, u32 chan) |
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{ |
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struct gpiomux *mux = data; |
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gpiomux_set(mux, mux->data.values[chan]); |
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return 0; |
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} |
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static int gpiomux_deselect(struct i2c_adapter *adap, void *data, u32 chan) |
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{ |
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struct gpiomux *mux = data; |
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gpiomux_set(mux, mux->data.idle); |
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return 0; |
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} |
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static int __devinit gpiomux_probe(struct platform_device *pdev) |
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{ |
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struct gpiomux *mux; |
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struct gpio_i2cmux_platform_data *pdata; |
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struct i2c_adapter *parent; |
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int (*deselect) (struct i2c_adapter *, void *, u32); |
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unsigned initial_state; |
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int i, ret; |
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pdata = pdev->dev.platform_data; |
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if (!pdata) { |
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dev_err(&pdev->dev, "Missing platform data\n"); |
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return -ENODEV; |
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} |
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parent = i2c_get_adapter(pdata->parent); |
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if (!parent) { |
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dev_err(&pdev->dev, "Parent adapter (%d) not found\n", |
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pdata->parent); |
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return -ENODEV; |
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} |
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mux = kzalloc(sizeof(*mux), GFP_KERNEL); |
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if (!mux) { |
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ret = -ENOMEM; |
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goto alloc_failed; |
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} |
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mux->parent = parent; |
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mux->data = *pdata; |
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mux->adap = kzalloc(sizeof(struct i2c_adapter *) * pdata->n_values, |
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GFP_KERNEL); |
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if (!mux->adap) { |
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ret = -ENOMEM; |
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goto alloc_failed2; |
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} |
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if (pdata->idle != GPIO_I2CMUX_NO_IDLE) { |
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initial_state = pdata->idle; |
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deselect = gpiomux_deselect; |
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} else { |
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initial_state = pdata->values[0]; |
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deselect = NULL; |
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} |
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for (i = 0; i < pdata->n_gpios; i++) { |
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ret = gpio_request(pdata->gpios[i], "gpio-i2cmux"); |
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if (ret) |
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goto err_request_gpio; |
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gpio_direction_output(pdata->gpios[i], |
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initial_state & (1 << i)); |
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} |
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for (i = 0; i < pdata->n_values; i++) { |
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u32 nr = pdata->base_nr ? (pdata->base_nr + i) : 0; |
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mux->adap[i] = i2c_add_mux_adapter(parent, mux, nr, i, |
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gpiomux_select, deselect); |
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if (!mux->adap[i]) { |
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ret = -ENODEV; |
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dev_err(&pdev->dev, "Failed to add adapter %d\n", i); |
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goto add_adapter_failed; |
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} |
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} |
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dev_info(&pdev->dev, "%d port mux on %s adapter\n", |
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pdata->n_values, parent->name); |
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platform_set_drvdata(pdev, mux); |
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return 0; |
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add_adapter_failed: |
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for (; i > 0; i--) |
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i2c_del_mux_adapter(mux->adap[i - 1]); |
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i = pdata->n_gpios; |
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err_request_gpio: |
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for (; i > 0; i--) |
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gpio_free(pdata->gpios[i - 1]); |
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kfree(mux->adap); |
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alloc_failed2: |
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kfree(mux); |
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alloc_failed: |
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i2c_put_adapter(parent); |
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return ret; |
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} |
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static int __devexit gpiomux_remove(struct platform_device *pdev) |
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{ |
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struct gpiomux *mux = platform_get_drvdata(pdev); |
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int i; |
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for (i = 0; i < mux->data.n_values; i++) |
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i2c_del_mux_adapter(mux->adap[i]); |
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for (i = 0; i < mux->data.n_gpios; i++) |
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gpio_free(mux->data.gpios[i]); |
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platform_set_drvdata(pdev, NULL); |
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i2c_put_adapter(mux->parent); |
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kfree(mux->adap); |
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kfree(mux); |
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return 0; |
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} |
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static struct platform_driver gpiomux_driver = { |
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.probe = gpiomux_probe, |
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.remove = __devexit_p(gpiomux_remove), |
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.driver = { |
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.owner = THIS_MODULE, |
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.name = "gpio-i2cmux", |
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}, |
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}; |
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static int __init gpiomux_init(void) |
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{ |
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return platform_driver_register(&gpiomux_driver); |
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} |
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static void __exit gpiomux_exit(void) |
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{ |
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platform_driver_unregister(&gpiomux_driver); |
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} |
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module_init(gpiomux_init); |
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module_exit(gpiomux_exit); |
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MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver"); |
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MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>"); |
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MODULE_LICENSE("GPL"); |
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MODULE_ALIAS("platform:gpio-i2cmux"); |
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@ -0,0 +1,38 @@ |
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/*
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* gpio-i2cmux interface to platform code |
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* |
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* Peter Korsgaard <peter.korsgaard@barco.com> |
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* |
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* This program is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License version 2 as |
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* published by the Free Software Foundation. |
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*/ |
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#ifndef _LINUX_GPIO_I2CMUX_H |
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#define _LINUX_GPIO_I2CMUX_H |
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/* MUX has no specific idle mode */ |
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#define GPIO_I2CMUX_NO_IDLE ((unsigned)-1) |
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/**
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* struct gpio_i2cmux_platform_data - Platform-dependent data for gpio-i2cmux |
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* @parent: Parent I2C bus adapter number |
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* @base_nr: Base I2C bus number to number adapters from or zero for dynamic |
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* @values: Array of bitmasks of GPIO settings (low/high) for each |
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* position |
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* @n_values: Number of multiplexer positions (busses to instantiate) |
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* @gpios: Array of GPIO numbers used to control MUX |
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* @n_gpios: Number of GPIOs used to control MUX |
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* @idle: Bitmask to write to MUX when idle or GPIO_I2CMUX_NO_IDLE if not used |
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*/ |
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struct gpio_i2cmux_platform_data { |
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int parent; |
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int base_nr; |
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const unsigned *values; |
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int n_values; |
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const unsigned *gpios; |
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int n_gpios; |
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unsigned idle; |
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}; |
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#endif /* _LINUX_GPIO_I2CMUX_H */ |
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