diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/i2c/muxes/i2c-mux-gpio.c | 243 |
1 files changed, 243 insertions, 0 deletions
diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c new file mode 100644 index 000000000..4effe563e --- /dev/null +++ b/drivers/i2c/muxes/i2c-mux-gpio.c @@ -0,0 +1,243 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * I2C multiplexer using GPIO API + * + * Peter Korsgaard <peter.korsgaard@barco.com> + */ + +#include <linux/i2c.h> +#include <linux/i2c-mux.h> +#include <linux/platform_data/i2c-mux-gpio.h> +#include <linux/platform_device.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/bits.h> +#include <linux/gpio/consumer.h> +/* FIXME: stop poking around inside gpiolib */ +#include "../../gpio/gpiolib.h" + +struct gpiomux { + struct i2c_mux_gpio_platform_data data; + int ngpios; + struct gpio_desc **gpios; +}; + +static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val) +{ + DECLARE_BITMAP(values, BITS_PER_TYPE(val)); + + values[0] = val; + + gpiod_set_array_value_cansleep(mux->ngpios, mux->gpios, NULL, values); +} + +static int i2c_mux_gpio_select(struct i2c_mux_core *muxc, u32 chan) +{ + struct gpiomux *mux = i2c_mux_priv(muxc); + + i2c_mux_gpio_set(mux, chan); + + return 0; +} + +static int i2c_mux_gpio_deselect(struct i2c_mux_core *muxc, u32 chan) +{ + struct gpiomux *mux = i2c_mux_priv(muxc); + + i2c_mux_gpio_set(mux, mux->data.idle); + + return 0; +} + +#ifdef CONFIG_OF +static int i2c_mux_gpio_probe_dt(struct gpiomux *mux, + struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + struct device_node *adapter_np, *child; + struct i2c_adapter *adapter; + 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); + of_node_put(adapter_np); + if (!adapter) + return -EPROBE_DEFER; + + mux->data.parent = i2c_adapter_id(adapter); + put_device(&adapter->dev); + + mux->data.n_values = of_get_child_count(np); + + values = devm_kcalloc(&pdev->dev, + mux->data.n_values, sizeof(*mux->data.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_GPIO_NO_IDLE; + + return 0; +} +#else +static int i2c_mux_gpio_probe_dt(struct gpiomux *mux, + struct platform_device *pdev) +{ + return 0; +} +#endif + +static int i2c_mux_gpio_probe(struct platform_device *pdev) +{ + struct i2c_mux_core *muxc; + struct gpiomux *mux; + struct i2c_adapter *parent; + struct i2c_adapter *root; + unsigned initial_state; + int i, ngpios, ret; + + mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL); + if (!mux) + return -ENOMEM; + + if (!dev_get_platdata(&pdev->dev)) { + ret = i2c_mux_gpio_probe_dt(mux, pdev); + if (ret < 0) + return ret; + } else { + memcpy(&mux->data, dev_get_platdata(&pdev->dev), + sizeof(mux->data)); + } + + ngpios = gpiod_count(&pdev->dev, "mux"); + if (ngpios <= 0) { + dev_err(&pdev->dev, "no valid gpios provided\n"); + return ngpios ?: -EINVAL; + } + mux->ngpios = ngpios; + + parent = i2c_get_adapter(mux->data.parent); + if (!parent) + return -EPROBE_DEFER; + + muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values, + ngpios * sizeof(*mux->gpios), 0, + i2c_mux_gpio_select, NULL); + if (!muxc) { + ret = -ENOMEM; + goto alloc_failed; + } + mux->gpios = muxc->priv; + muxc->priv = mux; + + platform_set_drvdata(pdev, muxc); + + root = i2c_root_adapter(&parent->dev); + + muxc->mux_locked = true; + + if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) { + initial_state = mux->data.idle; + muxc->deselect = i2c_mux_gpio_deselect; + } else { + initial_state = mux->data.values[0]; + } + + for (i = 0; i < ngpios; i++) { + struct device *gpio_dev; + struct gpio_desc *gpiod; + enum gpiod_flags flag; + + if (initial_state & BIT(i)) + flag = GPIOD_OUT_HIGH; + else + flag = GPIOD_OUT_LOW; + gpiod = devm_gpiod_get_index(&pdev->dev, "mux", i, flag); + if (IS_ERR(gpiod)) { + ret = PTR_ERR(gpiod); + goto alloc_failed; + } + + mux->gpios[i] = gpiod; + + if (!muxc->mux_locked) + continue; + + /* FIXME: find a proper way to access the GPIO device */ + gpio_dev = &gpiod->gdev->dev; + muxc->mux_locked = i2c_root_adapter(gpio_dev) == root; + } + + if (muxc->mux_locked) + dev_info(&pdev->dev, "mux-locked i2c mux\n"); + + for (i = 0; i < mux->data.n_values; i++) { + u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0; + unsigned int class = mux->data.classes ? mux->data.classes[i] : 0; + + ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class); + if (ret) + goto add_adapter_failed; + } + + dev_info(&pdev->dev, "%d port mux on %s adapter\n", + mux->data.n_values, parent->name); + + return 0; + +add_adapter_failed: + i2c_mux_del_adapters(muxc); +alloc_failed: + i2c_put_adapter(parent); + + return ret; +} + +static int i2c_mux_gpio_remove(struct platform_device *pdev) +{ + struct i2c_mux_core *muxc = platform_get_drvdata(pdev); + + i2c_mux_del_adapters(muxc); + i2c_put_adapter(muxc->parent); + + return 0; +} + +static const struct of_device_id i2c_mux_gpio_of_match[] = { + { .compatible = "i2c-mux-gpio", }, + {}, +}; +MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match); + +static struct platform_driver i2c_mux_gpio_driver = { + .probe = i2c_mux_gpio_probe, + .remove = i2c_mux_gpio_remove, + .driver = { + .name = "i2c-mux-gpio", + .of_match_table = i2c_mux_gpio_of_match, + }, +}; + +module_platform_driver(i2c_mux_gpio_driver); + +MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver"); +MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:i2c-mux-gpio"); |