diff options
Diffstat (limited to 'drivers/i2c/muxes/gpio-i2cmux.c')
| -rw-r--r-- | drivers/i2c/muxes/gpio-i2cmux.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/drivers/i2c/muxes/gpio-i2cmux.c b/drivers/i2c/muxes/gpio-i2cmux.c new file mode 100644 index 000000000000..7b6ce624cd6e --- /dev/null +++ b/drivers/i2c/muxes/gpio-i2cmux.c @@ -0,0 +1,184 @@ +/* + * I2C multiplexer using GPIO API + * + * Peter Korsgaard <peter.korsgaard@barco.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/gpio-i2cmux.h> +#include <linux/platform_device.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/gpio.h> + +struct gpiomux { + struct i2c_adapter *parent; + struct i2c_adapter **adap; /* child busses */ + struct gpio_i2cmux_platform_data data; +}; + +static void gpiomux_set(const struct gpiomux *mux, unsigned val) +{ + int i; + + for (i = 0; i < mux->data.n_gpios; i++) + gpio_set_value(mux->data.gpios[i], val & (1 << i)); +} + +static int gpiomux_select(struct i2c_adapter *adap, void *data, u32 chan) +{ + struct gpiomux *mux = data; + + gpiomux_set(mux, mux->data.values[chan]); + + return 0; +} + +static int gpiomux_deselect(struct i2c_adapter *adap, void *data, u32 chan) +{ + struct gpiomux *mux = data; + + gpiomux_set(mux, mux->data.idle); + + return 0; +} + +static int __devinit gpiomux_probe(struct platform_device *pdev) +{ + struct gpiomux *mux; + struct gpio_i2cmux_platform_data *pdata; + struct i2c_adapter *parent; + int (*deselect) (struct i2c_adapter *, void *, u32); + unsigned initial_state; + int i, ret; + + pdata = pdev->dev.platform_data; + if (!pdata) { + dev_err(&pdev->dev, "Missing platform data\n"); + return -ENODEV; + } + + parent = i2c_get_adapter(pdata->parent); + if (!parent) { + dev_err(&pdev->dev, "Parent adapter (%d) not found\n", + pdata->parent); + return -ENODEV; + } + + mux = kzalloc(sizeof(*mux), GFP_KERNEL); + if (!mux) { + ret = -ENOMEM; + goto alloc_failed; + } + + mux->parent = parent; + mux->data = *pdata; + mux->adap = kzalloc(sizeof(struct i2c_adapter *) * pdata->n_values, + GFP_KERNEL); + if (!mux->adap) { + ret = -ENOMEM; + goto alloc_failed2; + } + + if (pdata->idle != GPIO_I2CMUX_NO_IDLE) { + initial_state = pdata->idle; + deselect = gpiomux_deselect; + } else { + initial_state = pdata->values[0]; + deselect = NULL; + } + + for (i = 0; i < pdata->n_gpios; i++) { + ret = gpio_request(pdata->gpios[i], "gpio-i2cmux"); + if (ret) + goto err_request_gpio; + gpio_direction_output(pdata->gpios[i], + initial_state & (1 << i)); + } + + for (i = 0; i < pdata->n_values; i++) { + u32 nr = pdata->base_nr ? (pdata->base_nr + i) : 0; + + mux->adap[i] = i2c_add_mux_adapter(parent, mux, nr, i, + gpiomux_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", + pdata->n_values, parent->name); + + platform_set_drvdata(pdev, mux); + + return 0; + +add_adapter_failed: + for (; i > 0; i--) + i2c_del_mux_adapter(mux->adap[i - 1]); + i = pdata->n_gpios; +err_request_gpio: + for (; i > 0; i--) + gpio_free(pdata->gpios[i - 1]); + kfree(mux->adap); +alloc_failed2: + kfree(mux); +alloc_failed: + i2c_put_adapter(parent); + + return ret; +} + +static int __devexit gpiomux_remove(struct platform_device *pdev) +{ + struct gpiomux *mux = platform_get_drvdata(pdev); + int i; + + for (i = 0; i < mux->data.n_values; i++) + i2c_del_mux_adapter(mux->adap[i]); + + for (i = 0; i < mux->data.n_gpios; i++) + gpio_free(mux->data.gpios[i]); + + platform_set_drvdata(pdev, NULL); + i2c_put_adapter(mux->parent); + kfree(mux->adap); + kfree(mux); + + return 0; +} + +static struct platform_driver gpiomux_driver = { + .probe = gpiomux_probe, + .remove = __devexit_p(gpiomux_remove), + .driver = { + .owner = THIS_MODULE, + .name = "gpio-i2cmux", + }, +}; + +static int __init gpiomux_init(void) +{ + return platform_driver_register(&gpiomux_driver); +} + +static void __exit gpiomux_exit(void) +{ + platform_driver_unregister(&gpiomux_driver); +} + +module_init(gpiomux_init); +module_exit(gpiomux_exit); + +MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver"); +MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:gpio-i2cmux"); |