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![Pierre-Louis Bossart](/assets/img/avatar_default.png)
The driver probe takes care of basic initialization and is invoked when a Slave becomes attached, after a match between the Slave DevID registers and ACPI/DT entries. The update_status callback is invoked when a Slave state changes, e.g. when it is assigned a non-zero Device Number and it reports with an ATTACHED/ALERT state. The state change detection is usually hardware-based and based on the SoundWire frame rate (e.g. double-digit microseconds) while the probe is a pure software operation, which may involve a kernel module load. In corner cases, it's possible that the state changes before the probe completes. This patch suggests the use of wait_for_completion to avoid races on startup, so that the update_status callback does not rely on invalid pointers/data structures. Signed-off-by: Rander Wang <rander.wang@intel.com> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> Link: https://lore.kernel.org/r/20200115000844.14695-2-pierre-louis.bossart@linux.intel.com Signed-off-by: Vinod Koul <vkoul@kernel.org>
200 lines
4.4 KiB
C
200 lines
4.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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// Copyright(c) 2015-17 Intel Corporation.
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#include <linux/module.h>
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#include <linux/mod_devicetable.h>
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#include <linux/pm_domain.h>
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#include <linux/soundwire/sdw.h>
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#include <linux/soundwire/sdw_type.h>
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#include "bus.h"
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/**
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* sdw_get_device_id - find the matching SoundWire device id
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* @slave: SoundWire Slave Device
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* @drv: SoundWire Slave Driver
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*
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* The match is done by comparing the mfg_id and part_id from the
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* struct sdw_device_id.
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*/
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static const struct sdw_device_id *
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sdw_get_device_id(struct sdw_slave *slave, struct sdw_driver *drv)
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{
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const struct sdw_device_id *id = drv->id_table;
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while (id && id->mfg_id) {
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if (slave->id.mfg_id == id->mfg_id &&
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slave->id.part_id == id->part_id)
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return id;
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id++;
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}
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return NULL;
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}
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static int sdw_bus_match(struct device *dev, struct device_driver *ddrv)
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{
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struct sdw_slave *slave = dev_to_sdw_dev(dev);
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struct sdw_driver *drv = drv_to_sdw_driver(ddrv);
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return !!sdw_get_device_id(slave, drv);
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}
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int sdw_slave_modalias(const struct sdw_slave *slave, char *buf, size_t size)
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{
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/* modalias is sdw:m<mfg_id>p<part_id> */
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return snprintf(buf, size, "sdw:m%04Xp%04X\n",
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slave->id.mfg_id, slave->id.part_id);
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}
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static int sdw_uevent(struct device *dev, struct kobj_uevent_env *env)
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{
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struct sdw_slave *slave = dev_to_sdw_dev(dev);
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char modalias[32];
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sdw_slave_modalias(slave, modalias, sizeof(modalias));
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if (add_uevent_var(env, "MODALIAS=%s", modalias))
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return -ENOMEM;
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return 0;
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}
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struct bus_type sdw_bus_type = {
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.name = "soundwire",
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.match = sdw_bus_match,
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.uevent = sdw_uevent,
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};
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EXPORT_SYMBOL_GPL(sdw_bus_type);
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static int sdw_drv_probe(struct device *dev)
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{
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struct sdw_slave *slave = dev_to_sdw_dev(dev);
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struct sdw_driver *drv = drv_to_sdw_driver(dev->driver);
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const struct sdw_device_id *id;
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int ret;
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id = sdw_get_device_id(slave, drv);
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if (!id)
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return -ENODEV;
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slave->ops = drv->ops;
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/*
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* attach to power domain but don't turn on (last arg)
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*/
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ret = dev_pm_domain_attach(dev, false);
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if (ret)
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return ret;
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ret = drv->probe(slave, id);
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if (ret) {
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dev_err(dev, "Probe of %s failed: %d\n", drv->name, ret);
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dev_pm_domain_detach(dev, false);
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return ret;
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}
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/* device is probed so let's read the properties now */
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if (slave->ops && slave->ops->read_prop)
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slave->ops->read_prop(slave);
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/*
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* Check for valid clk_stop_timeout, use DisCo worst case value of
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* 300ms
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*
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* TODO: check the timeouts and driver removal case
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*/
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if (slave->prop.clk_stop_timeout == 0)
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slave->prop.clk_stop_timeout = 300;
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slave->bus->clk_stop_timeout = max_t(u32, slave->bus->clk_stop_timeout,
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slave->prop.clk_stop_timeout);
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slave->probed = true;
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complete(&slave->probe_complete);
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dev_dbg(dev, "probe complete\n");
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return 0;
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}
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static int sdw_drv_remove(struct device *dev)
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{
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struct sdw_slave *slave = dev_to_sdw_dev(dev);
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struct sdw_driver *drv = drv_to_sdw_driver(dev->driver);
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int ret = 0;
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if (drv->remove)
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ret = drv->remove(slave);
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dev_pm_domain_detach(dev, false);
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return ret;
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}
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static void sdw_drv_shutdown(struct device *dev)
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{
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struct sdw_slave *slave = dev_to_sdw_dev(dev);
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struct sdw_driver *drv = drv_to_sdw_driver(dev->driver);
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if (drv->shutdown)
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drv->shutdown(slave);
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}
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/**
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* __sdw_register_driver() - register a SoundWire Slave driver
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* @drv: driver to register
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* @owner: owning module/driver
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*
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* Return: zero on success, else a negative error code.
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*/
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int __sdw_register_driver(struct sdw_driver *drv, struct module *owner)
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{
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drv->driver.bus = &sdw_bus_type;
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if (!drv->probe) {
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pr_err("driver %s didn't provide SDW probe routine\n",
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drv->name);
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return -EINVAL;
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}
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drv->driver.owner = owner;
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drv->driver.probe = sdw_drv_probe;
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if (drv->remove)
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drv->driver.remove = sdw_drv_remove;
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if (drv->shutdown)
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drv->driver.shutdown = sdw_drv_shutdown;
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return driver_register(&drv->driver);
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}
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EXPORT_SYMBOL_GPL(__sdw_register_driver);
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/**
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* sdw_unregister_driver() - unregisters the SoundWire Slave driver
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* @drv: driver to unregister
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*/
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void sdw_unregister_driver(struct sdw_driver *drv)
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{
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driver_unregister(&drv->driver);
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}
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EXPORT_SYMBOL_GPL(sdw_unregister_driver);
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static int __init sdw_bus_init(void)
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{
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sdw_debugfs_init();
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return bus_register(&sdw_bus_type);
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}
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static void __exit sdw_bus_exit(void)
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{
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sdw_debugfs_exit();
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bus_unregister(&sdw_bus_type);
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}
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postcore_initcall(sdw_bus_init);
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module_exit(sdw_bus_exit);
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MODULE_DESCRIPTION("SoundWire bus");
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MODULE_LICENSE("GPL v2");
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