情景分析
打算从两个角度来情景分析，先从bsp驱动工程师的角度，然后是驱动工程师的角度，下面以三星s3c6410 Pinctrl-samsung.c为例看看pinctrl输入参数的初始化过程（最开始的zynq平台的pin配置貌似是通过bitstreams来的，内核层没看到有关配置pin的代码，不过最新的zynq代码里加入了pinctrl，但我手上的恰好的较早其的zynq代码，所以这里以三星的代码为例子），不过这里贴的代码有点多（尽量将无关的代码删掉），耐心的看吧_
bsp驱动工程师的角度
static int samsung_pinctrl_probe(struct platform_device *pdev)
{
...
...
...
//解析pinctrl信息，后面分析
ctrl = samsung_pinctrl_get_soc_data(drvdata, pdev);
drvdata->ctrl = ctrl;
drvdata->dev = dev;
...
...
...
//向gpio子系统注册（三星有用gpio子系统）
ret = samsung_gpiolib_register(pdev, drvdata);
if (ret)
return ret;
//向pinctrl子系统注册
ret = samsung_pinctrl_register(pdev, drvdata);
if (ret) {
samsung_gpiolib_unregister(pdev, drvdata);
return ret;
}
...
...
...
return 0;
}
先贴下6410 pinctrl设备树信息(arch/arm/boot/dts/s3c64xx.dtsi)：
aliases {
i2c0 = &i2c0;
pinctrl0 = &pinctrl0;
};
pinctrl0: pinctrl@7f008000 {
compatible = "samsung,s3c64xx-pinctrl";
reg = <0x7f008000 0x1000>;
interrupt-parent = <&vic1>;
interrupts = <21>;
pctrl_int_map: pinctrl-interrupt-map {
interrupt-map = <0 &vic0 0>,
<1 &vic0 1>,
<2 &vic1 0>,
<3 &vic1 1>;
#address-cells = <0>;
#size-cells = <0>;
#interrupt-cells = <1>;
};
wakeup-interrupt-controller {
compatible = "samsung,s3c64xx-wakeup-eint";
interrupts = <0>, <1>, <2>, <3>;
interrupt-parent = <&pctrl_int_map>;
};
};
下面边看代码边对照上面的设备树描述，看看解析过程:
static struct samsung_pin_ctrl *samsung_pinctrl_get_soc_data(
struct samsung_pinctrl_drv_data *d,
struct platform_device *pdev)
{
int id;
const struct of_device_id *match;
struct device_node *node = pdev->dev.of_node;
struct device_node *np;
struct samsung_pin_ctrl *ctrl;
struct samsung_pin_bank *bank;
int i;
//获取pinctrl的alias id，其实就是上面的pinctrl0了
id = of_alias_get_id(node, "pinctrl");
if (id < 0) {
dev_err(&pdev->dev, "failed to get alias id
");
return NULL;
}
//获取该节点对应的match
match = of_match_node(samsung_pinctrl_dt_match, node);
//通过id找到对应的pinctrl，因为三星的有些soc是存在多个pinctrl的，
//也就是说pinctrl0，pinctrl1等等同时存在，这里就是获取第id个，对于6410，就一个
//struct samsung_pin_ctrl s3c64xx_pin_ctrl[] = {
// {
// /* pin-controller instance 1 data */
// .pin_banks = s3c64xx_pin_banks0,
// .nr_banks = ARRAY_SIZE(s3c64xx_pin_banks0),
// .eint_gpio_init = s3c64xx_eint_gpio_init,
// .eint_wkup_init = s3c64xx_eint_eint0_init,
// .label = "S3C64xx-GPIO",
// },
//};
对于exynos5420，就存在多个啦：
//struct samsung_pin_ctrl exynos5420_pin_ctrl[] = {
// {
// /* pin-controller instance 0 data */
// .pin_banks = exynos5420_pin_banks0,
// .nr_banks = ARRAY_SIZE(exynos5420_pin_banks0),
// .geint_con = EXYNOS_GPIO_ECON_OFFSET,
// .geint_mask = EXYNOS_GPIO_EMASK_OFFSET,
// .geint_pend = EXYNOS_GPIO_EPEND_OFFSET,
// .weint_con = EXYNOS_WKUP_ECON_OFFSET,
// .weint_mask = EXYNOS_WKUP_EMASK_OFFSET,
// .weint_pend = EXYNOS_WKUP_EPEND_OFFSET,
// .svc = EXYNOS_SVC_OFFSET,
// .eint_gpio_init = exynos_eint_gpio_init,
// .eint_wkup_init = exynos_eint_wkup_init,
// .label = "exynos5420-gpio-ctrl0",
// }, {
// /* pin-controller instance 1 data */
// .pin_banks = exynos5420_pin_banks1,
// .nr_banks = ARRAY_SIZE(exynos5420_pin_banks1),
// .geint_con = EXYNOS_GPIO_ECON_OFFSET,
// .geint_mask = EXYNOS_GPIO_EMASK_OFFSET,
// .geint_pend = EXYNOS_GPIO_EPEND_OFFSET,
// .svc = EXYNOS_SVC_OFFSET,
// .eint_gpio_init = exynos_eint_gpio_init,
// .label = "exynos5420-gpio-ctrl1",
// },
// ...
// ...
// ...
//};
ctrl = (struct samsung_pin_ctrl *)match->data + id;
//提取pin ctrl里的banks信息，这里就是ARRAY_SIZE(s3c64xx_pin_banks0)
bank = ctrl->pin_banks;
//遍历每一个bank，填充相应的信息
for (i = 0; i < ctrl->nr_banks; ++i, ++bank) {
spin_lock_init(&bank->slock);
bank->drvdata = d;
//设置bank的pin base
bank->pin_base = ctrl->nr_pins;
//更新ctrl->nr_pins，即该pin ctrl的pin数量，在后面的注册时会用到该成员
ctrl->nr_pins += bank->nr_pins;
}
//遍历该节点的每一个子节点，上面的s3c64xx.dtsi文件末尾有一个
//#include "s3c64xx-pinctrl.dtsi" 语句，s3c64xx-pinctrl.dtsi里
//的信息是对当前节点pinctrl0的补充，内容如下：
//&pinctrl0 {
///*
// * Pin banks
// */
//
//gpa: gpa {
// gpio-controller;
// #gpio-cells = <2>;
// interrupt-controller;
// #interrupt-cells = <2>;
//};
//
//gpb: gpb {
// gpio-controller;
// #gpio-cells = <2>;
// interrupt-controller;
// #interrupt-cells = <2>;
//};
//gpc: gpc {
// gpio-controller;
// #gpio-cells = <2>;
// interrupt-controller;
// #interrupt-cells = <2>;
//};
//...
//...
//...
//hsi_bus: hsi-bus {
// samsung,pins = "gpk-0", "gpk-1", "gpk-2", "gpk-3",
// "gpk-4", "gpk-5", "gpk-6", "gpk-7";
// samsung,pin-function = <3>;
// samsung,pin-pud = <PIN_PULL_NONE>;
//};
//}
//这里就是处理这些子节点
for_each_child_of_node(node, np) {
//如果该子节点没有gpio-controller属性，跳过处理，这里处理的是bank
//只和gpio有关，所以跳过不关心的
if (!of_find_property(np, "gpio-controller", NULL))
continue;
bank = ctrl->pin_banks;
for (i = 0; i < ctrl->nr_banks; ++i, ++bank) {
if (!strcmp(bank->name, np->name)) {
//将bank对应到它自己的设备节点
bank->of_node = np;
break;
}
}
}
ctrl->base = pin_base;
pin_base += ctrl->nr_pins;
return ctrl;
}
填充完必要的信息，就开始注册了，先看pinctrl的注册吧！注意，传入的参数drvdata是已经经过前面的解析填入了很多信息的
static int samsung_pinctrl_register(struct platform_device *pdev,
struct samsung_pinctrl_drv_data *drvdata)
{
struct pinctrl_desc *ctrldesc = &drvdata->pctl;
struct pinctrl_pin_desc *pindesc, *pdesc;
struct samsung_pin_bank *pin_bank;
char *pin_names;
int pin, bank, ret;
//初始化pinctrl_desc，register的时候要用
ctrldesc->name = "samsung-pinctrl";
ctrldesc->owner = THIS_MODULE;
//这个ops是必须要的，里面的几个函数前面也都用到了，主要有
//get_groups_count、dt_node_to_map、get_group_pins
ctrldesc->pctlops = &samsung_pctrl_ops;
//这个是pinctrl chip driver根据自己平台的特性，可选的支持的
//主要有request、get_functions_count、get_function_groups、
//enable，和gpio相关的还有额外几个gpio_request_enable、gpio_disable_free、gpio_set_direction
ctrldesc->pmxops = &samsung_pinmux_ops;
//这个是pinctrl chip driver根据自己平台的特性，可选的支持的
//主要有pin_config_get、pin_config_set、pin_config_group_get、pin_config_group_set
ctrldesc->confops = &samsung_pinconf_ops;
//下面这部分也是pinctrl chip driver根据自己平台的特性必须填充的，用于表示该pinctrl chip
//所有的pin信息
pindesc = devm_kzalloc(&pdev->dev, sizeof(*pindesc) *
drvdata->ctrl->nr_pins, GFP_KERNEL);
if (!pindesc) {
dev_err(&pdev->dev, "mem alloc for pin descriptors failed
");
return -ENOMEM;
}
ctrldesc->pins = pindesc;
ctrldesc->npins = drvdata->ctrl->nr_pins;//该成员就是samsung_pin_ctrl填充的
//填充pin号
/* dynamically populate the pin number and pin name for pindesc */
for (pin = 0, pdesc = pindesc; pin < ctrldesc->npins; pin++, pdesc++)
pdesc->number = pin + drvdata->ctrl->base;//该成员也是由samsung_pin_ctrl填充的
//分配空间，用于填充pin名字
/*
* allocate space for storing the dynamically generated names for all
* the pins which belong to this pin-controller.
*/
pin_names = devm_kzalloc(&pdev->dev, sizeof(char) * PIN_NAME_LENGTH *
drvdata->ctrl->nr_pins, GFP_KERNEL);
if (!pin_names) {
dev_err(&pdev->dev, "mem alloc for pin names failed
");
return -ENOMEM;
}
/* for each pin, the name of the pin is pin-bank name + pin number */
for (bank = 0; bank < drvdata->ctrl->nr_banks; bank++) {
pin_bank = &drvdata->ctrl->pin_banks[bank];
for (pin = 0; pin < pin_bank->nr_pins; pin++) {
//填充pin的名字，注意这里的格式，设备树里的命名就得按照该格式，即bank名字+pin号
sprintf(pin_names, "%s-%d", pin_bank->name, pin);
pdesc = pindesc + pin_bank->pin_base + pin;
pdesc->name = pin_names;
pin_names += PIN_NAME_LENGTH;
}
}
//到现在，离注册需要的条件就剩function和group的填充了，其实它们不是pinctrl子系统要求的，
//但是回调函数的实现依赖这些，因此需要解析设备树信息来填充它们，后面会详细分析该函数
ret = samsung_pinctrl_parse_dt(pdev, drvdata);
if (ret)
return ret;
//一切准备好后，就注册了
drvdata->pctl_dev = pinctrl_register(ctrldesc, &pdev->dev, drvdata);
if (!drvdata->pctl_dev) {
dev_err(&pdev->dev, "could not register pinctrl driver
");
return -EINVAL;
}
//
for (bank = 0; bank < drvdata->ctrl->nr_banks; ++bank) {
pin_bank = &drvdata->ctrl->pin_banks[bank];
pin_bank->grange.name = pin_bank->name;
pin_bank->grange.id = bank;
pin_bank->grange.pin_base = pin_bank->pin_base;
pin_bank->grange.base = pin_bank->gpio_chip.base;
pin_bank->grange.npins = pin_bank->gpio_chip.ngpio;
pin_bank->grange.gc = &pin_bank->gpio_chip;
pinctrl_add_gpio_range(drvdata->pctl_dev, &pin_bank->grange);
}
return 0;
}
samsung_pinctrl_parse_dt分析：
static int samsung_pinctrl_parse_dt(struct platform_device *pdev,
struct samsung_pinctrl_drv_data *drvdata)
{
...
//获取pinctrl设备的子节点数量，前面已经讲过有哪些子节点了，不再重复
grp_cnt = of_get_child_count(dev_np);
if (!grp_cnt)
return -EINVAL;
//根据获取的数量，分配空间，每个配置节点对应于一个group（pin的集合）
groups = devm_kzalloc(dev, grp_cnt * sizeof(*groups), GFP_KERNEL);
if (!groups) {
dev_err(dev, "failed allocate memory for ping group list
");
return -EINVAL;
}
grp = groups;
//根据获取的数量，分配空间，每个配置节点对应的功能
functions = devm_kzalloc(dev, grp_cnt * sizeof(*functions), GFP_KERNEL);
if (!functions) {
dev_err(dev, "failed to allocate memory for function list
");
return -EINVAL;
}
func = functions;
//遍历每一个子节点，一个个处理
/*
* Iterate over all the child nodes of the pin controller node
* and create pin groups and pin function lists.
*/
for_each_child_of_node(dev_np, cfg_np) {
u32 function;
//检查samsung,pins属性
if (!of_find_property(cfg_np, "samsung,pins", NULL))
continue;
//将samsung,pins属性里面指定的名字列表转换为pin号列表
//，这里面会用到前面samsung_pinctrl_get_soc_data填充的信息来匹配
ret = samsung_pinctrl_parse_dt_pins(pdev, cfg_np,
&drvdata->pctl, &pin_list, &npins);
if (ret)
return ret;
//下面就是构成一个pin group了，注意pin组的名字
//，是配置节点名+GROUP_SUFFIX，GROUP_SUFFIX为-grp
/* derive pin group name from the node name */
gname = devm_kzalloc(dev, strlen(cfg_np->name) + GSUFFIX_LEN,
GFP_KERNEL);
if (!gname) {
dev_err(dev, "failed to alloc memory for group name
");
return -ENOMEM;
}
sprintf(gname, "%s%s", cfg_np->name, GROUP_SUFFIX);
grp->name = gname;
grp->pins = pin_list;
grp->num_pins = npins;
of_property_read_u32(cfg_np, "samsung,pin-function", &function);
grp->func = function;
grp++;
if (!of_find_property(cfg_np, "samsung,pin-function", NULL))
continue;
//如果存在samsung,pin-function属性，那么构建一个功能名
//，功能名组合方式是配置节点名+FUNCTION_SUFFIX，FUNCTION_SUFFIX为-mux
/* derive function name from the node name */
fname = devm_kzalloc(dev, strlen(cfg_np->name) + FSUFFIX_LEN,
GFP_KERNEL);
if (!fname) {
dev_err(dev, "failed to alloc memory for func name
");
return -ENOMEM;
}
sprintf(fname, "%s%s", cfg_np->name, FUNCTION_SUFFIX);
func->name = fname;
func->groups = devm_kzalloc(dev, sizeof(char *), GFP_KERNEL);
if (!func->groups) {
dev_err(dev, "failed to alloc memory for group list "
"in pin function");
return -ENOMEM;
}
func->groups[0] = gname;
func->num_groups = 1;
func++;
func_idx++;
}
//存储下解析的数据信息
drvdata->pin_groups = groups;
drvdata->nr_groups = grp_cnt;
drvdata->pmx_functions = functions;
drvdata->nr_functions = func_idx;
return 0;
}
下面通过分析各个ops，来进一步理解下上面几个函数所起的作用：
static const struct pinctrl_ops samsung_pctrl_ops = {
.get_groups_count = samsung_get_group_count,
.get_group_name = samsung_get_group_name,
.get_group_pins = samsung_get_group_pins,
.dt_node_to_map = samsung_dt_node_to_map,
.dt_free_map = samsung_dt_free_map,
};
static const struct pinmux_ops samsung_pinmux_ops = {
.get_functions_count = samsung_get_functions_count,
.get_function_name = samsung_pinmux_get_fname,
.get_function_groups = samsung_pinmux_get_groups,
.enable = samsung_pinmux_enable,
.disable = samsung_pinmux_disable,
//由pinmux_gpio_direction间接调用，最开始应该是gpio子系统
//的gpio_pin_direction_input、gpio_pin_direction_output触发
.gpio_set_direction = samsung_pinmux_gpio_set_direction,
};
static const struct pinconf_ops samsung_pinconf_ops = {
.pin_config_get = samsung_pinconf_get,
.pin_config_set = samsung_pinconf_set,
.pin_config_group_get = samsung_pinconf_group_get,
.pin_config_group_set = samsung_pinconf_group_set,
};
从上面一路分析下路来，我们应该知道dt_node_to_map是最先调用的，其次是get_functions_count、get_function_name、get_function_groups、get_groups_count、get_group_name、get_group_pins、request（三星pinmux_ops没有实现它）、enable、pin_config_set、pin_config_group_set所以我打算就按这个顺序进行分析。
调用dt_node_to_map的时候，从前文应该很清楚了吧，就是在某一个设备（pinctrl本身也算是一个设备，不过从前文贴出来的pinctrl0里，我没发现有pinctrl-xxx的属性，也就是说不需要对它做任何pin ctrl）用pinctrl_get请求解析自己设备树信息的时候，说的更准确点的话，就是解析该设备里某一个状态的某一个配置（一个状态可能需要多个配置来完成）的时候。下面用某一个子设备的设备树信息为例子，对应文件s3c6410-smdk6410.dts
#define PIN_PULL_NONE 0
&uart0 {
pinctrl-names = "default";
pinctrl-0 = <&uart0_data>, <&uart0_fctl>;
status = "okay";
};
uart0_data: uart0-data {
samsung,pins = "gpa-0", "gpa-1";
samsung,pin-function = <2>;
samsung,pin-pud = <PIN_PULL_NONE>;
};
uart0_fctl: uart0-fctl {
samsung,pins = "gpa-2", "gpa-3";
samsung,pin-function = <2>;
samsung,pin-pud = <PIN_PULL_NONE>;
};
//下面部分是uart0的其他信息，和本文关心的pinctrl无关，之所以也列出来，只是不想让读者对这部分有误解
uart0: serial@7f005000 {
compatible = "samsung,s3c6400-uart";
reg = <0x7f005000 0x100>;
interrupt-parent = <&vic1>;
interrupts = <5>;
clock-names = "uart", "clk_uart_baud2",
"clk_uart_baud3";
clocks = <&clocks PCLK_UART0>, <&clocks PCLK_UART0>,
<&clocks SCLK_UART>;
status = "disabled";
};
对应的解析代码如下，从前文描述应该清楚，期望回调函数返回该设备该状态该配置下的所有设置信息（可能只存在mux设置，也可能同时存在mux和conf设置），而上面的设备树里的uart0只有一个状态，default，对应的配置有两个，一个是uart0_data，一个是uart0_fctl，它们都是对配置节点的引用，配置节点都是pinctrl节点下的子节点，下面看代码吧：
static int samsung_dt_node_to_map(struct pinctrl_dev *pctldev,
struct device_node *np, struct pinctrl_map **maps,
unsigned *nmaps)
{
...
//检查该节点（第一次调用应该是uart0_data节点，第二次调用应该是uart0_fctl节点啦）
//含有多少个自己定义的属性，包括：
//{ "samsung,pin-pud", PINCFG_TYPE_PUD },
//{ "samsung,pin-drv", PINCFG_TYPE_DRV },
//{ "samsung,pin-con-pdn", PINCFG_TYPE_CON_PDN },
//{ "samsung,pin-pud-pdn", PINCFG_TYPE_PUD_PDN },
/* count the number of config options specfied in the node */
for (idx = 0; idx < ARRAY_SIZE(pcfgs); idx++) {
if (of_find_property(np, pcfgs[idx].prop_cfg, NULL))
cfg_cnt++;
}
/*
* Find out the number of map entries to create. All the config options
* can be accomadated into a single config map entry.
*/
//如果有，那么说明需要继续后面的conf操作
if (cfg_cnt)
map_cnt = 1;
//如果存在samsung,pin-function属性，那么不仅要做后面的操作，还需要额外做一些mux操作
if (of_find_property(np, "samsung,pin-function", NULL))
map_cnt++;
if (!map_cnt) {
dev_err(dev, "node %s does not have either config or function "
"configurations
", np->name);
return -EINVAL;
}
//分配空间
/* Allocate memory for pin-map entries */
map = kzalloc(sizeof(*map) * map_cnt, GFP_KERNEL);
if (!map) {
dev_err(dev, "could not alloc memory for pin-maps
");
return -ENOMEM;
}
*nmaps = 0;
//从前面的分析应该清楚了组名的格式，下面就是根据配置节点名构建一个格式，然后到系统
//里找对应的信息
/*
* Allocate memory for pin group name. The pin group name is derived
* from the node name from which these map entries are be created.
*/
gname = kzalloc(strlen(np->name) + GSUFFIX_LEN, GFP_KERNEL);
if (!gname) {
dev_err(dev, "failed to alloc memory for group name
");
goto free_map;
}
sprintf(gname, "%s%s", np->name, GROUP_SUFFIX);
/*
* don't have config options? then skip over to creating function
* map entries.
*/
if (!cfg_cnt)
goto skip_cfgs;
//根据前面获取的数量来分配配置节点空间
/* Allocate memory for config entries */
cfg = kzalloc(sizeof(*cfg) * cfg_cnt, GFP_KERNEL);
if (!cfg) {
dev_err(dev, "failed to alloc memory for configs
");
goto free_gname;
}
//将已经定义的，属于自己定义列表里面的属性值提取出来，对应于我们这里，都是PIN_PULL_NONE
/* Prepare a list of config settings */
for (idx = 0, cfg_cnt = 0; idx < ARRAY_SIZE(pcfgs); idx++) {
u32 value;
if (!of_property_read_u32(np, pcfgs[idx].prop_cfg, &value))
cfg[cfg_cnt++] =
PINCFG_PACK(pcfgs[idx].cfg_type, value);
}
//创建设置信息，如设置名字，类型，以及多少个conf操作，每一个conf值
/* create the config map entry */
map[*nmaps].data.configs.group_or_pin = gname;
map[*nmaps].data.configs.configs = cfg;
map[*nmaps].data.configs.num_configs = cfg_cnt;
map[*nmaps].type = PIN_MAP_TYPE_CONFIGS_GROUP;
*nmaps += 1;
skip_cfgs:
/* create the function map entry */
if (of_find_property(np, "samsung,pin-function", NULL)) {
//如果存在samsung,pin-function属性，说明有mux的需求，处理它
//这里是构建功能名，和前面初始化的时候一致
fname = kzalloc(strlen(np->name) + FSUFFIX_LEN, GFP_KERNEL);
if (!fname) {
dev_err(dev, "failed to alloc memory for func name
");
goto free_cfg;
}
sprintf(fname, "%s%s", np->name, FUNCTION_SUFFIX);
//填充mux操作需要的信息，如哪一个设备，哪一个功能
map[*nmaps].data.mux.group = gname;
map[*nmaps].data.mux.function = fname;
map[*nmaps].type = PIN_MAP_TYPE_MUX_GROUP;
*nmaps += 1;
}
*maps = map;
return 0;
...
}
samsung_get_functions_count，它用于获取功能的总数量drvdata->nr_functions，前面已经分析过初始化这个的过程，所以这里就不再分析。samsung_pinmux_get_fname从已经初始化的数据结构里拿出对应索引上的name，name就是由配置节点名＋-mux后缀构成。pinctrl_get的过程（pinmux_map_to_setting），会以map->data.mux.function为参数调用samsung_pinmux_get_fname获取该功能对应的索引来初始化setting->data.mux.func，然后在用samsung_pinmux_get_groups获取的组信息里，用前面解析出来的map[*nmaps].data.mux.group作为输入参数，获取该组的索引来初始化setting->data.mux.group。最后在pinctrl_select_state的时候，会通过上面的信息并结合最开始初始化的一些数据结构进行mux和conf操作。pinconf_map_to_setting的操作类似，不再重复。在pinctrl_select_state的时候samsung_pinmux_enable和samsung_pinconf_set有可能会触发，这里就不再继续分析了，但还是贴出代码吧！
/* enable a specified pinmux by writing to registers */
static int samsung_pinmux_enable(struct pinctrl_dev *pctldev, unsigned selector,
unsigned group)
{
samsung_pinmux_setup(pctldev, selector, group, true);
return 0;
}
static void samsung_pinmux_setup(struct pinctrl_dev *pctldev, unsigned selector,
unsigned group, bool enable)
{
struct samsung_pinctrl_drv_data *drvdata;
const unsigned int *pins;
struct samsung_pin_bank *bank;
void __iomem *reg;
u32 mask, shift, data, pin_offset, cnt;
unsigned long flags;
drvdata = pinctrl_dev_get_drvdata(pctldev);
pins = drvdata->pin_groups[group].pins;
/*
* for each pin in the pin group selected, program the correspoding pin
* pin function number in the config register.
*/
for (cnt = 0; cnt < drvdata->pin_groups[group].num_pins; cnt++) {
struct samsung_pin_bank_type *type;
pin_to_reg_bank(drvdata, pins[cnt] - drvdata->ctrl->base,
®, &pin_offset, &bank);
type = bank->type;
mask = (1 << type->fld_width[PINCFG_TYPE_FUNC]) - 1;
shift = pin_offset * type->fld_width[PINCFG_TYPE_FUNC];
if (shift >= 32) {
/* Some banks have two config registers */
shift -= 32;
reg += 4;
}
spin_lock_irqsave(&bank->slock, flags);
data = readl(reg + type->reg_offset[PINCFG_TYPE_FUNC]);
data &= ~(mask << shift);
if (enable)
data |= drvdata->pin_groups[group].func << shift;
writel(data, reg + type->reg_offset[PINCFG_TYPE_FUNC]);
spin_unlock_irqrestore(&bank->slock, flags);
}
}
/* set the pin config settings for a specified pin */
static int samsung_pinconf_set(struct pinctrl_dev *pctldev, unsigned int pin,
unsigned long *configs, unsigned num_configs)
{
int i, ret;
for (i = 0; i < num_configs; i++) {
ret = samsung_pinconf_rw(pctldev, pin, &configs[i], true);
if (ret < 0)
return ret;
} /* for each config */
return 0;
}
/* set or get the pin config settings for a specified pin */
static int samsung_pinconf_rw(struct pinctrl_dev *pctldev, unsigned int pin,
unsigned long *config, bool set)
{
struct samsung_pinctrl_drv_data *drvdata;
struct samsung_pin_bank_type *type;
struct samsung_pin_bank *bank;
void __iomem *reg_base;
enum pincfg_type cfg_type = PINCFG_UNPACK_TYPE(*config);
u32 data, width, pin_offset, mask, shift;
u32 cfg_value, cfg_reg;
unsigned long flags;
drvdata = pinctrl_dev_get_drvdata(pctldev);
pin_to_reg_bank(drvdata, pin - drvdata->ctrl->base, ®_base,
&pin_offset, &bank);
type = bank->type;
if (cfg_type >= PINCFG_TYPE_NUM || !type->fld_width[cfg_type])
return -EINVAL;
width = type->fld_width[cfg_type];
cfg_reg = type->reg_offset[cfg_type];
spin_lock_irqsave(&bank->slock, flags);
mask = (1 << width) - 1;
shift = pin_offset * width;
data = readl(reg_base + cfg_reg);
if (set) {
cfg_value = PINCFG_UNPACK_VALUE(*config);
data &= ~(mask << shift);
data |= (cfg_value << shift);
writel(data, reg_base + cfg_reg);
} else {
data >>= shift;
data &= mask;
*config = PINCFG_PACK(cfg_type, data);
}
spin_unlock_irqrestore(&bank->slock, flags);
return 0;
}
/* set the pin config settings for a specified pin group */
static int samsung_pinconf_group_set(struct pinctrl_dev *pctldev,
unsigned group, unsigned long *configs,
unsigned num_configs)
{
struct samsung_pinctrl_drv_data *drvdata;
const unsigned int *pins;
unsigned int cnt;
drvdata = pinctrl_dev_get_drvdata(pctldev);
pins = drvdata->pin_groups[group].pins;
for (cnt = 0; cnt < drvdata->pin_groups[group].num_pins; cnt++)
samsung_pinconf_set(pctldev, pins[cnt], configs, num_configs);
return 0;
}
驱动工程师的角度
一般会用到的接口：
devm_pinctrl_get
pinctrl_lookup_state
pinctrl_select_state
操作gpio时，会用到的接口：
pinctrl_request_gpio
pinctrl_gpio_direction_input
pinctrl_gpio_direction_output
还有一些额外变体，懒得贴了
下面以gpio方式的api为例子继续分析，这样也好与文章最开始的gpio子系统结合起来理解！pinctrl_request_gpio在驱动里，主要有两类会用到它，一类是gpio子系统的实现者，即gpio-xxx.c那些文件，另一类是pinctrl的实现者，即pinctrl-xxx.c那些文件。它们在注册gpio chip时，将pinctrl_request_gpio作为gpio chip里request，这样间接将pinctrl操作交给gpio子系统自动完成。从gpio子系统分析可知，request的调用是在gpio_request或者gpiod_get间接触发。看一下pinctrl_request_gpio做了些什么：
int pinctrl_request_gpio(unsigned gpio)
{
struct pinctrl_dev *pctldev;
struct pinctrl_gpio_range *range;
int ret;
int pin;
//这里会通过gpio来取得该gpio对应的pctldev和range，还记得分析gpiochip_add时的
//of_gpiochip_add_pin_range吧，这里就用到了它add的信息
ret = pinctrl_get_device_gpio_range(gpio, &pctldev, &range);
if (ret) {
if (pinctrl_ready_for_gpio_range(gpio))
ret = 0;
return ret;
}
mutex_lock(&pctldev->mutex);
/* Convert to the pin controllers number space */
//有了range就好办了啦，它里面有gpio与pin号的对应关系，当然这关系是最开始从设备树里解析过来的
pin = gpio_to_pin(range, gpio);
//有了所有信息调用pinmux_request_gpio进一步request吧
ret = pinmux_request_gpio(pctldev, range, pin, gpio);
mutex_unlock(&pctldev->mutex);
return ret;
}
继续pinmux_request_gpio：
int pinmux_request_gpio(struct pinctrl_dev *pctldev,
struct pinctrl_gpio_range *range,
unsigned pin, unsigned gpio)
{
const char *owner;
int ret;
/* Conjure some name stating what chip and pin this is taken by */
owner = kasprintf(GFP_KERNEL, "%s:%d", range->name, gpio);
if (!owner)
return -EINVAL;
//pin_request之前分析的时候有看到调用过，不过这次gpio的时候会传入range，导致它的
//调用流程会有所不同，里面会触发pinmux_ops的gpio_request_enable回调，而不是request回调
ret = pin_request(pctldev, pin, owner, range);
if (ret < 0)
kfree(owner);
return ret;
}
最后看看设备驱动模型中pinctrl的影子，在bus_probe_device的时候，会调用device_attach，而device_attach里会调用__device_attach去attach，在匹配成功后，会调用driver_probe_device，它会导致really_probe的调用来进行驱动的probe，最终会导致pinctrl_bind_pins调用，这个函数会pinctrl_get并设置设备的初始状态，这个过程不需要驱动额外做任何事情，多么巧妙啊
int pinctrl_bind_pins(struct device *dev)
{
int ret;
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
");
ret = PTR_ERR(dev->pins->p);
goto cleanup_alloc;
}
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
");
ret = 0;
goto cleanup_get;
}
ret = pinctrl_select_state(dev->pins->p, dev->pins->default_state);
if (ret) {
dev_dbg(dev, "failed to activate default pinctrl state
");
goto cleanup_get;
}
...
}
总结
通过对gpio子系统和pinctrl子系统的分析，应该对这两个系统有了大致的概念了吧_ gpio子系统让驱动工程师不用关心底层gpio chip的具体实现，让bsp工程师不用关心上层驱动工程师的使用方式。pinctrl子系统帮我们管理了pin信息，包括了pin的mux和conf，同时也透明的处理了与gpio子系统的关联以及设备模型的关联。
完！
2015年7月