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pinctrl驱动----驱动/设备侧

作者:互联网

具有pinctrl需要的设备初始化

1. 故事的开始

static int really_probe(struct device *dev, struct device_driver *drv)
{
	dev->driver = drv;

	/* If using pinctrl, bind pins now before probing */
	ret = pinctrl_bind_pins(dev);
	if (ret)
		goto pinctrl_bind_failed;

	if (dev->bus->dma_configure) {
		ret = dev->bus->dma_configure(dev);
		if (ret)
			goto dma_failed;
	}

	if (driver_sysfs_add(dev)) {
		printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
			__func__, dev_name(dev));
		goto probe_failed;
	}

	if (dev->pm_domain && dev->pm_domain->activate) {
		ret = dev->pm_domain->activate(dev);
		if (ret)
			goto probe_failed;
	}

	if (dev->bus->probe) {
		ret = dev->bus->probe(dev);
		if (ret)
			goto probe_failed;
	} else if (drv->probe) {
		ret = drv->probe(dev);
		if (ret)
			goto probe_failed;
	}

}

在设备的probe函数执行之前,会执行pinctrl相关的引脚初始化和配置。同时从上面的函数我们可以看出:Linux内核会提前处理pinctrldma等硬件设备的请求,让驱动开发变得尽量少的直接接触硬件。

2. 故事的概述

这里我去掉了一些不相关或者不重要的函数,重点分析函数执行的核心流程和关键代码

/**
 * pinctrl_bind_pins() - called by the device core before probe
 * @dev: the device that is just about to probe
 */
int pinctrl_bind_pins(struct device *dev)
{
	int ret;

	if (dev->of_node_reused)
		return 0;

	dev->pins = devm_kzalloc(dev, sizeof(*(dev->pins)), GFP_KERNEL);
	if (!dev->pins)
		return -ENOMEM;

	dev->pins->p = devm_pinctrl_get(dev);
	if (IS_ERR(dev->pins->p)) {
		dev_dbg(dev, "no pinctrl handle\n");
		ret = PTR_ERR(dev->pins->p);
		goto cleanup_alloc;
	}

	/* defualt 状态的检查: 一般都采取defualt的配置 */
	dev->pins->default_state = pinctrl_lookup_state(dev->pins->p,
					PINCTRL_STATE_DEFAULT);
	if (IS_ERR(dev->pins->default_state)) {
		dev_dbg(dev, "no default pinctrl state\n");
		ret = 0;
		goto cleanup_get;
	}

	/* init状态的检查 :一般没有该设置*/
	dev->pins->init_state = pinctrl_lookup_state(dev->pins->p,
					PINCTRL_STATE_INIT);
	if (IS_ERR(dev->pins->init_state)) {
		/* Not supplying this state is perfectly legal */
		dev_dbg(dev, "no init pinctrl state\n");

		ret = pinctrl_select_state(dev->pins->p,					//该函数在定义了default之后会被执行
					   dev->pins->default_state);
	} else {
		ret = pinctrl_select_state(dev->pins->p, dev->pins->init_state);		//该函数在定义了init属性后会被执行
	}

	if (ret) {
		dev_dbg(dev, "failed to activate initial pinctrl state\n");
		goto cleanup_get;
	}
	
	/* 这里去掉了功耗相关的代码 */
	
	return 0;

cleanup_get:
	devm_pinctrl_put(dev->pins->p);
cleanup_alloc:
	devm_kfree(dev, dev->pins);
	dev->pins = NULL;

	/* Return deferrals */
	if (ret == -EPROBE_DEFER)
		return ret;
	/* Return serious errors */
	if (ret == -EINVAL)
		return ret;
	/* We ignore errors like -ENOENT meaning no pinctrl state */

	return 0;
}

这里我总结一下重要的函数在哪,这也是众多解析文章会替到的:

3. 第一个大片场面


/**
 * struct devm_pinctrl_get() - Resource managed pinctrl_get()
 * @dev: the device to obtain the handle for
 *
 * If there is a need to explicitly destroy the returned struct pinctrl,
 * devm_pinctrl_put() should be used, rather than plain pinctrl_put().
 */
struct pinctrl *devm_pinctrl_get(struct device *dev)
{
	struct pinctrl **ptr, *p;

	ptr = devres_alloc(devm_pinctrl_release, sizeof(*ptr), GFP_KERNEL);
	if (!ptr)
		return ERR_PTR(-ENOMEM);

	p = pinctrl_get(dev);
	if (!IS_ERR(p)) {
		*ptr = p;
		devres_add(dev, ptr);
	} else {
		devres_free(ptr);
	}

	return p;
}
EXPORT_SYMBOL_GPL(devm_pinctrl_get);

具体的设备获取函数:

/**
 * pinctrl_get() - retrieves the pinctrl handle for a device
 * @dev: the device to obtain the handle for
 */
struct pinctrl *pinctrl_get(struct device *dev)
{
	struct pinctrl *p;

	if (WARN_ON(!dev))
		return ERR_PTR(-EINVAL);

	/*
	 * See if somebody else (such as the device core) has already
	 * obtained a handle to the pinctrl for this device. In that case,
	 * return another pointer to it.
	 */
	p = find_pinctrl(dev);
	if (p) {
		dev_dbg(dev, "obtain a copy of previously claimed pinctrl\n");
		kref_get(&p->users);
		return p;
	}

	return create_pinctrl(dev, NULL);
}
EXPORT_SYMBOL_GPL(pinctrl_get);

pinctrl的查找:在设备驱动中应该是找不到的

static struct pinctrl *find_pinctrl(struct device *dev)
{
	struct pinctrl *p;

	mutex_lock(&pinctrl_list_mutex);
	list_for_each_entry(p, &pinctrl_list, node)
		if (p->dev == dev) {
			mutex_unlock(&pinctrl_list_mutex);
			return p;
		}

	mutex_unlock(&pinctrl_list_mutex);
	return NULL;
}

理论上来说,这里应该是找不到的。所以会调用后面的create_pinctrl函数构造一个。下面便开始解析这个函数是如何够找的。

第二个重要函数点

设备的pinctrl的注册

参数解析:
dev: 设备的dev结构体
pctldev: NULL

static struct pinctrl *create_pinctrl(struct device *dev,
				      struct pinctrl_dev *pctldev)
{
	struct pinctrl *p;
	const char *devname;
	struct pinctrl_maps *maps_node;
	int i;
	const struct pinctrl_map *map;
	int ret;

	/*
	 * create the state cookie holder struct pinctrl for each
	 * mapping, this is what consumers will get when requesting
	 * a pin control handle with pinctrl_get()
	 */
	p = kzalloc(sizeof(*p), GFP_KERNEL);
	if (!p)
		return ERR_PTR(-ENOMEM);
	p->dev = dev;
	INIT_LIST_HEAD(&p->states);
	INIT_LIST_HEAD(&p->dt_maps);

	ret = pinctrl_dt_to_map(p, pctldev);
	if (ret < 0) {
		kfree(p);
		return ERR_PTR(ret);
	}

	devname = dev_name(dev);

	mutex_lock(&pinctrl_maps_mutex);
	/* Iterate over the pin control maps to locate the right ones */
	for_each_maps(maps_node, i, map) {
		/* Map must be for this device */
		if (strcmp(map->dev_name, devname))
			continue;
		/*
		 * If pctldev is not null, we are claiming hog for it,
		 * that means, setting that is served by pctldev by itself.
		 *
		 * Thus we must skip map that is for this device but is served
		 * by other device.
		 */
		if (pctldev &&
		    strcmp(dev_name(pctldev->dev), map->ctrl_dev_name))
			continue;

		ret = add_setting(p, pctldev, map);
		/*
		 * At this point the adding of a setting may:
		 *
		 * - Defer, if the pinctrl device is not yet available
		 * - Fail, if the pinctrl device is not yet available,
		 *   AND the setting is a hog. We cannot defer that, since
		 *   the hog will kick in immediately after the device
		 *   is registered.
		 *
		 * If the error returned was not -EPROBE_DEFER then we
		 * accumulate the errors to see if we end up with
		 * an -EPROBE_DEFER later, as that is the worst case.
		 */
		if (ret == -EPROBE_DEFER) {
			pinctrl_free(p, false);
			mutex_unlock(&pinctrl_maps_mutex);
			return ERR_PTR(ret);
		}
	}
	mutex_unlock(&pinctrl_maps_mutex);

	if (ret < 0) {
		/* If some other error than deferral occurred, return here */
		pinctrl_free(p, false);
		return ERR_PTR(ret);
	}

	kref_init(&p->users);

	/* Add the pinctrl handle to the global list */
	mutex_lock(&pinctrl_list_mutex);
	list_add_tail(&p->node, &pinctrl_list);
	mutex_unlock(&pinctrl_list_mutex);

	return p;
}

创建pinctrl的函数


int pinctrl_dt_to_map(struct pinctrl *p, struct pinctrl_dev *pctldev)
{
	struct device_node *np = p->dev->of_node;
	int state, ret;
	char *propname;
	struct property *prop;
	const char *statename;
	const __be32 *list;
	int size, config;
	phandle phandle;
	struct device_node *np_config;

	/* CONFIG_OF enabled, p->dev not instantiated from DT */
	if (!np) {
		if (of_have_populated_dt())
			dev_dbg(p->dev,
				"no of_node; not parsing pinctrl DT\n");
		return 0;
	}

	/* We may store pointers to property names within the node */
	of_node_get(np);

	/* For each defined state ID */
	for (state = 0; ; state++) {				//轮询pinctrl-n属性
		/* 1. Retrieve the pinctrl-* property :取回/找回 pinctrl-n的属性*/
		propname = kasprintf(GFP_KERNEL, "pinctrl-%d", state);
		prop = of_find_property(np, propname, &size);
		kfree(propname);
		if (!prop) {
			if (state == 0) {
				of_node_put(np);
				return -ENODEV;
			}
			break;
		}
		list = prop->value;
		size /= sizeof(*list);

		/* 2.  Determine whether pinctrl-names property names the state 
		这里取回设备定义的状态信息,state作为一个index指示读取的数据
		statename 保存了读取的数据 
		*/
		ret = of_property_read_string_index(np, "pinctrl-names",
						    state, &statename);
		/*
		 * If not, statename is just the integer state ID. But rather
		 * than dynamically allocate it and have to free it later,
		 * just point part way into the property name for the string.
		 */
		if (ret < 0) {
			/* strlen("pinctrl-") == 8 */
			statename = prop->name + 8;
		}

		/* For every referenced pin configuration node in it
		* 这里是处理的一个核心所在
		 */
		for (config = 0; config < size; config++) {
			phandle = be32_to_cpup(list++);

			/* Look up the pin configuration node: 查找pinctrl配置的节点 */
			np_config = of_find_node_by_phandle(phandle);
			if (!np_config) {
				dev_err(p->dev,
					"prop %s index %i invalid phandle\n",
					prop->name, config);
				ret = -EINVAL;
				goto err;
			}

			/* Parse the node */
			ret = dt_to_map_one_config(p, pctldev, statename,
						   np_config);
			of_node_put(np_config);			//配置完成后去掉对该节点的引用
			if (ret < 0)
				goto err;
		}

		/* No entries in DT? Generate a dummy state table entry */
		if (!size) {			//size属性错误的处理
			ret = dt_remember_dummy_state(p, statename);
			if (ret < 0)
				goto err;
		}
	}

	return 0;

err:
	pinctrl_dt_free_maps(p);
	return ret;
}

这里的函数个人认为非常重要,所以会细致的分析该函数的作用和执行流程:

下面分析一个映射的实现:

static int dt_to_map_one_config(struct pinctrl *p,
				struct pinctrl_dev *hog_pctldev,
				const char *statename,
				struct device_node *np_config)
{
	struct pinctrl_dev *pctldev = NULL;
	struct device_node *np_pctldev;
	const struct pinctrl_ops *ops;
	int ret;
	struct pinctrl_map *map;
	unsigned num_maps;
	bool allow_default = false;

	/* Find the pin controller containing np_config */
	np_pctldev = of_node_get(np_config);
	for (;;) {
		if (!allow_default)
			allow_default = of_property_read_bool(np_pctldev,
							      "pinctrl-use-default");

		np_pctldev = of_get_next_parent(np_pctldev);
		if (!np_pctldev || of_node_is_root(np_pctldev)) {
			of_node_put(np_pctldev);
			ret = driver_deferred_probe_check_state(p->dev);
			/* keep deferring if modules are enabled unless we've timed out */
			if (IS_ENABLED(CONFIG_MODULES) && !allow_default && ret == -ENODEV)
				ret = -EPROBE_DEFER;

			return ret;
		}
		/* If we're creating a hog we can use the passed pctldev */
		if (hog_pctldev && (np_pctldev == p->dev->of_node)) {
			pctldev = hog_pctldev;
			break;
		}
		pctldev = get_pinctrl_dev_from_of_node(np_pctldev);
		if (pctldev)
			break;
		/* Do not defer probing of hogs (circular loop) */
		if (np_pctldev == p->dev->of_node) {
			of_node_put(np_pctldev);
			return -ENODEV;
		}
	}
	of_node_put(np_pctldev);

	/*
	 * Call pinctrl driver to parse device tree node, and
	 * generate mapping table entries
	 */
	ops = pctldev->desc->pctlops;
	if (!ops->dt_node_to_map) {
		dev_err(p->dev, "pctldev %s doesn't support DT\n",
			dev_name(pctldev->dev));
		return -ENODEV;
	}
	ret = ops->dt_node_to_map(pctldev, np_config, &map, &num_maps);
	if (ret < 0)
		return ret;

	/* Stash the mapping table chunk away for later use */
	return dt_remember_or_free_map(p, statename, pctldev, map, num_maps);
}

这里的函数主要具有两个功能

上面的函数先分析到这里,下面的函数更加精彩!

4. 第二个大片场面

1. 状态查找函数
这里会根据状态去查找相应的pinctrl_state结构。

/**
 * pinctrl_lookup_state() - retrieves a state handle from a pinctrl handle
 * @p: the pinctrl handle to retrieve the state from
 * @name: the state name to retrieve
 */
struct pinctrl_state *pinctrl_lookup_state(struct pinctrl *p,
						 const char *name)
{
	struct pinctrl_state *state;

	state = find_state(p, name);
	if (!state) {
		if (pinctrl_dummy_state) {
			/* create dummy state */
			dev_dbg(p->dev, "using pinctrl dummy state (%s)\n",
				name);
			state = create_state(p, name);
		} else
			state = ERR_PTR(-ENODEV);
	}

	return state;
}
EXPORT_SYMBOL_GPL(pinctrl_lookup_state);

static struct pinctrl_state *find_state(struct pinctrl *p,
					const char *name)
{
	struct pinctrl_state *state;

	list_for_each_entry(state, &p->states, node)
		if (!strcmp(state->name, name))
			return state;

	return NULL;
}

2. 查找到对应的状态后如何初始化
这里先说明:我们的分析是以设备的defualt状态设置来分析的,在具体的设备树中,我们也主要使用defualt这个默认属性

/**
 * pinctrl_select_state() - select/activate/program a pinctrl state to HW
 * @p: the pinctrl handle for the device that requests configuration
 * @state: the state handle to select/activate/program
 */
int pinctrl_select_state(struct pinctrl *p, struct pinctrl_state *state)
{
	if (p->state == state)
		return 0;

	return pinctrl_commit_state(p, state);
}
EXPORT_SYMBOL_GPL(pinctrl_select_state);

下面便是具体执行的流程:

/**
 * pinctrl_commit_state() - select/activate/program a pinctrl state to HW
 * @p: the pinctrl handle for the device that requests configuration
 * @state: the state handle to select/activate/program
 */
static int pinctrl_commit_state(struct pinctrl *p, struct pinctrl_state *state)
{
	struct pinctrl_setting *setting, *setting2;
	struct pinctrl_state *old_state = p->state;
	int ret;

	if (p->state) {
		/*
		 * For each pinmux setting in the old state, forget SW's record
		 * of mux owner for that pingroup. Any pingroups which are
		 * still owned by the new state will be re-acquired by the call
		 * to pinmux_enable_setting() in the loop below.
		 */
		list_for_each_entry(setting, &p->state->settings, node) {
			if (setting->type != PIN_MAP_TYPE_MUX_GROUP)
				continue;
			pinmux_disable_setting(setting);
		}
	}

	p->state = NULL;

	/* Apply all the settings for the new state */
	list_for_each_entry(setting, &state->settings, node) {
		switch (setting->type) {
		case PIN_MAP_TYPE_MUX_GROUP:
			ret = pinmux_enable_setting(setting);
			break;
		case PIN_MAP_TYPE_CONFIGS_PIN:
		case PIN_MAP_TYPE_CONFIGS_GROUP:
			ret = pinconf_apply_setting(setting);
			break;
		default:
			ret = -EINVAL;
			break;
		}

		if (ret < 0) {
			goto unapply_new_state;
		}
	}

	p->state = state;

	return 0;
}

这里我去掉了和错误处理有关的函数,分析其中的核心函数!我们可以看到,这里会根据设置的类型调用不同的函数进行设置处理,下面详细的分析一下这两个函数的执行流程:

int pinmux_enable_setting(const struct pinctrl_setting *setting)
{
	struct pinctrl_dev *pctldev = setting->pctldev;
	const struct pinctrl_ops *pctlops = pctldev->desc->pctlops;
	const struct pinmux_ops *ops = pctldev->desc->pmxops;
	int ret = 0;
	const unsigned *pins = NULL;
	unsigned num_pins = 0;
	int i;
	struct pin_desc *desc;

	if (pctlops->get_group_pins)
		ret = pctlops->get_group_pins(pctldev, setting->data.mux.group,
					      &pins, &num_pins);

	if (ret) {
		const char *gname;

		/* errors only affect debug data, so just warn */
		gname = pctlops->get_group_name(pctldev,
						setting->data.mux.group);
		dev_warn(pctldev->dev,
			 "could not get pins for group %s\n",
			 gname);
		num_pins = 0;
	}

	/* Try to allocate all pins in this group, one by one */
	for (i = 0; i < num_pins; i++) {
		ret = pin_request(pctldev, pins[i], setting->dev_name, NULL);
		if (ret) {
			const char *gname;
			const char *pname;

			desc = pin_desc_get(pctldev, pins[i]);
			pname = desc ? desc->name : "non-existing";
			gname = pctlops->get_group_name(pctldev,
						setting->data.mux.group);
			dev_err(pctldev->dev,
				"could not request pin %d (%s) from group %s "
				" on device %s\n",
				pins[i], pname, gname,
				pinctrl_dev_get_name(pctldev));
			goto err_pin_request;
		}
	}

	/* Now that we have acquired the pins, encode the mux setting */
	for (i = 0; i < num_pins; i++) {
		desc = pin_desc_get(pctldev, pins[i]);
		if (desc == NULL) {
			dev_warn(pctldev->dev,
				 "could not get pin desc for pin %d\n",
				 pins[i]);
			continue;
		}
		desc->mux_setting = &(setting->data.mux);
	}

	ret = ops->set_mux(pctldev, setting->data.mux.func,
			   setting->data.mux.group);

	if (ret)
		goto err_set_mux;

	return 0;

err_set_mux:
	for (i = 0; i < num_pins; i++) {
		desc = pin_desc_get(pctldev, pins[i]);
		if (desc)
			desc->mux_setting = NULL;
	}
err_pin_request:
	/* On error release all taken pins */
	while (--i >= 0)
		pin_free(pctldev, pins[i], NULL);

	return ret;
}

int pinconf_apply_setting(const struct pinctrl_setting *setting)
{
	struct pinctrl_dev *pctldev = setting->pctldev;
	const struct pinconf_ops *ops = pctldev->desc->confops;
	int ret;

	if (!ops) {
		dev_err(pctldev->dev, "missing confops\n");
		return -EINVAL;
	}

	switch (setting->type) {
	case PIN_MAP_TYPE_CONFIGS_PIN:
		if (!ops->pin_config_set) {
			dev_err(pctldev->dev, "missing pin_config_set op\n");
			return -EINVAL;
		}
		ret = ops->pin_config_set(pctldev,
				setting->data.configs.group_or_pin,
				setting->data.configs.configs,
				setting->data.configs.num_configs);
		if (ret < 0) {
			dev_err(pctldev->dev,
				"pin_config_set op failed for pin %d\n",
				setting->data.configs.group_or_pin);
			return ret;
		}
		break;
	case PIN_MAP_TYPE_CONFIGS_GROUP:
		if (!ops->pin_config_group_set) {
			dev_err(pctldev->dev,
				"missing pin_config_group_set op\n");
			return -EINVAL;
		}
		ret = ops->pin_config_group_set(pctldev,
				setting->data.configs.group_or_pin,
				setting->data.configs.configs,
				setting->data.configs.num_configs);
		if (ret < 0) {
			dev_err(pctldev->dev,
				"pin_config_group_set op failed for group %d\n",
				setting->data.configs.group_or_pin);
			return ret;
		}
		break;
	default:
		return -EINVAL;
	}

	return 0;
}

到这里设备侧的函数执行流程便已经结束

标签:struct,pinctrl,dev,pctldev,----,state,ret,驱动
来源: https://www.cnblogs.com/weirdo-xo/p/14337942.html