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author | Wolfram Sang <wsa+renesas@sang-engineering.com> | 2016-01-13 14:29:27 (GMT) |
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committer | Wolfram Sang <wsa@the-dreams.de> | 2016-02-12 18:16:04 (GMT) |
commit | 50a5ba876908147b36441c754e835588143c6b54 (patch) | |
tree | c280d50a5f6d1a4fde1537a13e87cd423cb775bd /drivers/i2c | |
parent | 388f7b1d6e8ca06762e2454d28d6c3c55ad0fe95 (diff) | |
download | linux-50a5ba876908147b36441c754e835588143c6b54.tar.xz |
i2c: mux: demux-pinctrl: add driver
This driver allows an I2C bus to switch between multiple masters. This
is not hot-switching because connected I2C slaves will be
re-instantiated. It is meant to select the best I2C core at runtime once
the task is known. Example: Prefer i2c-gpio over another I2C core
because of HW errata affecting your use case.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c')
-rw-r--r-- | drivers/i2c/muxes/Kconfig | 9 | ||||
-rw-r--r-- | drivers/i2c/muxes/Makefile | 2 | ||||
-rw-r--r-- | drivers/i2c/muxes/i2c-demux-pinctrl.c | 272 |
3 files changed, 283 insertions, 0 deletions
diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig index f06b0e2..e280c8e 100644 --- a/drivers/i2c/muxes/Kconfig +++ b/drivers/i2c/muxes/Kconfig @@ -72,4 +72,13 @@ config I2C_MUX_REG This driver can also be built as a module. If so, the module will be called i2c-mux-reg. +config I2C_DEMUX_PINCTRL + tristate "pinctrl-based I2C demultiplexer" + depends on PINCTRL && OF + select OF_DYNAMIC + help + If you say yes to this option, support will be included for an I2C + demultiplexer that uses the pinctrl subsystem. This is useful if you + want to change the I2C master at run-time depending on features. + endmenu diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile index e89799b..7c267c2 100644 --- a/drivers/i2c/muxes/Makefile +++ b/drivers/i2c/muxes/Makefile @@ -3,6 +3,8 @@ obj-$(CONFIG_I2C_ARB_GPIO_CHALLENGE) += i2c-arb-gpio-challenge.o +obj-$(CONFIG_I2C_DEMUX_PINCTRL) += i2c-demux-pinctrl.o + obj-$(CONFIG_I2C_MUX_GPIO) += i2c-mux-gpio.o obj-$(CONFIG_I2C_MUX_PCA9541) += i2c-mux-pca9541.o obj-$(CONFIG_I2C_MUX_PCA954x) += i2c-mux-pca954x.o diff --git a/drivers/i2c/muxes/i2c-demux-pinctrl.c b/drivers/i2c/muxes/i2c-demux-pinctrl.c new file mode 100644 index 0000000..7748a0a --- /dev/null +++ b/drivers/i2c/muxes/i2c-demux-pinctrl.c @@ -0,0 +1,272 @@ +/* + * Pinctrl based I2C DeMultiplexer + * + * Copyright (C) 2015-16 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com> + * Copyright (C) 2015-16 by Renesas Electronics Corporation + * + * 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; version 2 of the License. + * + * See the bindings doc for DTS setup and the sysfs doc for usage information. + * (look for filenames containing 'i2c-demux-pinctrl' in Documentation/) + */ + +#include <linux/i2c.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/pinctrl/consumer.h> +#include <linux/platform_device.h> +#include <linux/slab.h> +#include <linux/sysfs.h> + +struct i2c_demux_pinctrl_chan { + struct device_node *parent_np; + struct i2c_adapter *parent_adap; + struct of_changeset chgset; +}; + +struct i2c_demux_pinctrl_priv { + int cur_chan; + int num_chan; + struct device *dev; + const char *bus_name; + struct i2c_adapter cur_adap; + struct i2c_algorithm algo; + struct i2c_demux_pinctrl_chan chan[]; +}; + +static struct property status_okay = { .name = "status", .length = 3, .value = "ok" }; + +static int i2c_demux_master_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) +{ + struct i2c_demux_pinctrl_priv *priv = adap->algo_data; + struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap; + + return __i2c_transfer(parent, msgs, num); +} + +static u32 i2c_demux_functionality(struct i2c_adapter *adap) +{ + struct i2c_demux_pinctrl_priv *priv = adap->algo_data; + struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap; + + return parent->algo->functionality(parent); +} + +static int i2c_demux_activate_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan) +{ + struct i2c_adapter *adap; + struct pinctrl *p; + int ret; + + ret = of_changeset_apply(&priv->chan[new_chan].chgset); + if (ret) + goto err; + + adap = of_find_i2c_adapter_by_node(priv->chan[new_chan].parent_np); + if (!adap) { + ret = -ENODEV; + goto err; + } + + p = devm_pinctrl_get_select(adap->dev.parent, priv->bus_name); + if (IS_ERR(p)) { + ret = PTR_ERR(p); + goto err_with_put; + } + + priv->chan[new_chan].parent_adap = adap; + priv->cur_chan = new_chan; + + /* Now fill out current adapter structure. cur_chan must be up to date */ + priv->algo.master_xfer = i2c_demux_master_xfer; + priv->algo.functionality = i2c_demux_functionality; + + snprintf(priv->cur_adap.name, sizeof(priv->cur_adap.name), + "i2c-demux (master i2c-%d)", i2c_adapter_id(adap)); + priv->cur_adap.owner = THIS_MODULE; + priv->cur_adap.algo = &priv->algo; + priv->cur_adap.algo_data = priv; + priv->cur_adap.dev.parent = priv->dev; + priv->cur_adap.class = adap->class; + priv->cur_adap.retries = adap->retries; + priv->cur_adap.timeout = adap->timeout; + priv->cur_adap.quirks = adap->quirks; + priv->cur_adap.dev.of_node = priv->dev->of_node; + ret = i2c_add_adapter(&priv->cur_adap); + if (ret < 0) + goto err_with_put; + + return 0; + + err_with_put: + i2c_put_adapter(adap); + err: + dev_err(priv->dev, "failed to setup demux-adapter %d (%d)\n", new_chan, ret); + return ret; +} + +static int i2c_demux_deactivate_master(struct i2c_demux_pinctrl_priv *priv) +{ + int ret, cur = priv->cur_chan; + + if (cur < 0) + return 0; + + i2c_del_adapter(&priv->cur_adap); + i2c_put_adapter(priv->chan[cur].parent_adap); + + ret = of_changeset_revert(&priv->chan[cur].chgset); + + priv->chan[cur].parent_adap = NULL; + priv->cur_chan = -EINVAL; + + return ret; +} + +static int i2c_demux_change_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan) +{ + int ret; + + if (new_chan == priv->cur_chan) + return 0; + + ret = i2c_demux_deactivate_master(priv); + if (ret) + return ret; + + return i2c_demux_activate_master(priv, new_chan); +} + +static ssize_t cur_master_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev); + int count = 0, i; + + for (i = 0; i < priv->num_chan && count < PAGE_SIZE; i++) + count += scnprintf(buf + count, PAGE_SIZE - count, "%c %d - %s\n", + i == priv->cur_chan ? '*' : ' ', i, + priv->chan[i].parent_np->full_name); + + return count; +} + +static ssize_t cur_master_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev); + unsigned int val; + int ret; + + ret = kstrtouint(buf, 0, &val); + if (ret < 0) + return ret; + + if (val >= priv->num_chan) + return -EINVAL; + + ret = i2c_demux_change_master(priv, val); + + return ret < 0 ? ret : count; +} +static DEVICE_ATTR_RW(cur_master); + +static int i2c_demux_pinctrl_probe(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + struct i2c_demux_pinctrl_priv *priv; + int num_chan, i, j, err; + + num_chan = of_count_phandle_with_args(np, "i2c-parent", NULL); + if (num_chan < 2) { + dev_err(&pdev->dev, "Need at least two I2C masters to switch\n"); + return -EINVAL; + } + + priv = devm_kzalloc(&pdev->dev, sizeof(*priv) + + num_chan * sizeof(struct i2c_demux_pinctrl_chan), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + err = of_property_read_string(np, "i2c-bus-name", &priv->bus_name); + if (err) + return err; + + for (i = 0; i < num_chan; i++) { + struct device_node *adap_np; + + adap_np = of_parse_phandle(np, "i2c-parent", i); + if (!adap_np) { + dev_err(&pdev->dev, "can't get phandle for parent %d\n", i); + err = -ENOENT; + goto err_rollback; + } + priv->chan[i].parent_np = adap_np; + + of_changeset_init(&priv->chan[i].chgset); + of_changeset_update_property(&priv->chan[i].chgset, adap_np, &status_okay); + } + + priv->num_chan = num_chan; + priv->dev = &pdev->dev; + + platform_set_drvdata(pdev, priv); + + /* switch to first parent as active master */ + i2c_demux_activate_master(priv, 0); + + err = device_create_file(&pdev->dev, &dev_attr_cur_master); + if (err) + goto err_rollback; + + return 0; + +err_rollback: + for (j = 0; j < i; j++) { + of_node_put(priv->chan[j].parent_np); + of_changeset_destroy(&priv->chan[j].chgset); + } + + return err; +} + +static int i2c_demux_pinctrl_remove(struct platform_device *pdev) +{ + struct i2c_demux_pinctrl_priv *priv = platform_get_drvdata(pdev); + int i; + + device_remove_file(&pdev->dev, &dev_attr_cur_master); + + i2c_demux_deactivate_master(priv); + + for (i = 0; i < priv->num_chan; i++) { + of_node_put(priv->chan[i].parent_np); + of_changeset_destroy(&priv->chan[i].chgset); + } + + return 0; +} + +static const struct of_device_id i2c_demux_pinctrl_of_match[] = { + { .compatible = "i2c-demux-pinctrl", }, + {}, +}; +MODULE_DEVICE_TABLE(of, i2c_demux_pinctrl_of_match); + +static struct platform_driver i2c_demux_pinctrl_driver = { + .driver = { + .name = "i2c-demux-pinctrl", + .of_match_table = i2c_demux_pinctrl_of_match, + }, + .probe = i2c_demux_pinctrl_probe, + .remove = i2c_demux_pinctrl_remove, +}; +module_platform_driver(i2c_demux_pinctrl_driver); + +MODULE_DESCRIPTION("pinctrl-based I2C demux driver"); +MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>"); +MODULE_LICENSE("GPL v2"); +MODULE_ALIAS("platform:i2c-demux-pinctrl"); |