对电子商务网站建设的理解,建站平台加盟,网站开发相关知识,网站运营的含义本文主要分析#xff1a; 1. i2c设备注册 2. i2c驱动注册 3. 上层调用过程参考#xff1a; http://www.cnblogs.com/helloworldtoyou/p/5126618.html1. i2c设备注册
kernel/arch/arm/mach-mx6/board-mx6q_sabresd.c … 本文主要分析 1. i2c设备注册 2. i2c驱动注册 3. 上层调用过程参考 http://www.cnblogs.com/helloworldtoyou/p/5126618.html1. i2c设备注册
kernel/arch/arm/mach-mx6/board-mx6q_sabresd.c
static void __init mx6_sabresd_board_init(void)
{ mxc_iomux_v3_setup_multiple_pads(mx6q_sabresd_pads, --------------- ARRAY_SIZE(mx6q_sabresd_pads)); | ... ... | strcpy(mxc_i2c0_board_info[0].type, wm8962); | mxc_i2c0_board_info[0].platform_data wm8962_config_data; | | //注册i2c总线 | imx6q_add_imx_i2c(0, mx6q_sabresd_i2c_data); ------------ | imx6q_add_imx_i2c(1, mx6q_sabresd_i2c_data); ---- | | imx6q_add_imx_i2c(2, mx6q_sabresd_i2c_data); | | | | | | i2c_register_board_info(0, mxc_i2c0_board_info, ---------------- | ARRAY_SIZE(mxc_i2c0_board_info)); | | | | i2c_register_board_info(1, mxc_i2c1_board_info, | | | | ARRAY_SIZE(mxc_i2c1_board_info)); | | | | i2c_register_board_info(2, mxc_i2c2_board_info, | | | | ARRAY_SIZE(mxc_i2c2_board_info)); | | | | ... ... | | | |
} | | | | | | | |
static iomux_v3_cfg_t mx6q_sabresd_pads[] { ----------|-----|-- /* I2C1, WM8958 */ | | | MX6Q_PAD_CSI0_DAT8__I2C1_SDA, | | | MX6Q_PAD_CSI0_DAT9__I2C1_SCL, | | | | | | /* I2C2, Camera, MIPI */ | | | MX6Q_PAD_KEY_COL3__I2C2_SCL, | | | MX6Q_PAD_KEY_ROW3__I2C2_SDA, | | | | | |
#ifdef CONFIG_MX6_ENET_IRQ_TO_GPIO | | | MX6Q_PAD_GPIO_6__OBSERVE_MUX_OBSRV_INT_OUT1, | | |
#else | | | /* I2C3 */ | | | MX6Q_PAD_GPIO_3__I2C3_SCL, /* GPIO1[3] */ | | | MX6Q_PAD_GPIO_6__I2C3_SDA, | | |
#endif | | |
}; | | | | | |
//总线速率 V | |
static struct imxi2c_platform_data mx6q_sabresd_i2c_data { | | .bitrate 100000, | |
}; | | | |
#define imx6q_add_imx_i2c(id, pdata) \ ----------- | imx_add_imx_i2c(imx6q_imx_i2c_data[id], pdata) | | | |
struct platform_device *__init imx_add_imx_i2c( ----------- | const struct imx_imx_i2c_data *data, | const struct imxi2c_platform_data *pdata) |
{ | struct resource res[] { | { | .start data-iobase, | .end data-iobase data-iosize - 1, | .flags IORESOURCE_MEM, | }, { | .start data-irq, | .end data-irq, | .flags IORESOURCE_IRQ, | }, | }; | | return imx_add_platform_device(imx-i2c, data-id, | res, ARRAY_SIZE(res), | pdata, sizeof(*pdata)); |
} | |
//指定i2c链接设备的名称和地址 |
static struct i2c_board_info mxc_i2c0_board_info[] __initdata { - { | I2C_BOARD_INFO(wm89**, 0x1a), | }, | /* | { | I2C_BOARD_INFO(ov564x, 0x3c), | .platform_data (void *)camera_data, | }, | { | I2C_BOARD_INFO(mma8451, 0x1d), | .platform_data (void *)mma8451_position, | }, | { | I2C_BOARD_INFO(isl1208, 0x6f), | }, | */ |
}; | |
int __init |
i2c_register_board_info(int busnum, ------------------ struct i2c_board_info const *info, unsigned len)
{ int status; down_write(__i2c_board_lock); //动态更新总线个数 /* dynamic bus numbers will be assigned after the last static one */ if (busnum __i2c_first_dynamic_bus_num) __i2c_first_dynamic_bus_num busnum 1; //将同一个i2c接口的所有设备都添加到一个链表中 for (status 0; len; len--, info) { struct i2c_devinfo *devinfo; devinfo kzalloc(sizeof(*devinfo), GFP_KERNEL); if (!devinfo) { pr_debug(i2c-core: cant register boardinfo!\n); status -ENOMEM; break; } devinfo-busnum busnum; devinfo-board_info *info; list_add_tail(devinfo-list, __i2c_board_list); } up_write(__i2c_board_lock); return status;
} 2. i2c驱动注册
kernel/drivers/i2c/busses/i2c-imx.c
static int __init i2c_adap_imx_init(void)
{ return platform_driver_probe(i2c_imx_driver, i2c_imx_probe); ----------
} | |
int __init_or_module platform_driver_probe(struct platform_driver *drv, | int (*probe)(struct platform_device *)) |
{ | int retval, code; | | drv-driver.suppress_bind_attrs true; | //指定驱动的probe函数 | drv-probe probe; | //注册平台驱动 | retval code platform_driver_register(drv); | | spin_lock(drv-driver.bus-p-klist_drivers.k_lock); | drv-probe NULL; | if (code 0 list_empty(drv-driver.p-klist_devices.k_list)) | retval -ENODEV; | drv-driver.probe platform_drv_probe_fail; | spin_unlock(drv-driver.bus-p-klist_drivers.k_lock); | | if (code ! retval) | platform_driver_unregister(drv); | return retval; |
} |
EXPORT_SYMBOL_GPL(platform_driver_probe); | |
static struct platform_driver i2c_imx_driver { ----------------- .remove __exit_p(i2c_imx_remove), | .driver { | .name DRIVER_NAME, // imx-i2c | .owner THIS_MODULE, | } |
}; | |
static int __init i2c_imx_probe(struct platform_device *pdev) ---------
{ struct imx_i2c_struct *i2c_imx; struct resource *res; struct imxi2c_platform_data *pdata; void __iomem *base; resource_size_t res_size; int irq; int ret; dev_dbg(pdev-dev, %s\n, __func__); //获得i2c寄存器地址的信息 res platform_get_resource(pdev, IORESOURCE_MEM, 0); if (!res) { dev_err(pdev-dev, cant get device resources\n); return -ENOENT; } irq platform_get_irq(pdev, 0); if (irq 0) { dev_err(pdev-dev, cant get irq number\n); return -ENOENT; } pdata pdev-dev.platform_data; if (pdata pdata-init) { ret pdata-init(pdev-dev); if (ret) return ret; } res_size resource_size(res); if (!request_mem_region(res-start, res_size, DRIVER_NAME)) { ret -EBUSY; goto fail0; } base ioremap(res-start, res_size); if (!base) { dev_err(pdev-dev, ioremap failed\n); ret -EIO; goto fail1; } i2c_imx kzalloc(sizeof(struct imx_i2c_struct), GFP_KERNEL); if (!i2c_imx) { dev_err(pdev-dev, cant allocate interface\n); ret -ENOMEM; goto fail2; } /* Setup i2c_imx driver structure */ strcpy(i2c_imx-adapter.name, pdev-name); i2c_imx-adapter.owner THIS_MODULE; i2c_imx-adapter.algo i2c_imx_algo; // i2c算法 ---------------i2c_imx-adapter.dev.parent pdev-dev; | i2c_imx-adapter.nr pdev-id; | i2c_imx-irq irq; | i2c_imx-base base; | i2c_imx-res res; | | /* Get I2C clock */ | i2c_imx-clk clk_get(pdev-dev, i2c_clk); | if (IS_ERR(i2c_imx-clk)) { | ret PTR_ERR(i2c_imx-clk); | dev_err(pdev-dev, cant get I2C clock\n); | goto fail3; | } | | /* Request IRQ */ | ret request_irq(i2c_imx-irq, i2c_imx_isr, 0, pdev-name, i2c_imx); | if (ret) { | dev_err(pdev-dev, cant claim irq %d\n, i2c_imx-irq); | goto fail4; | } | | /* Init queue */ | init_waitqueue_head(i2c_imx-queue); | | /* Set up adapter data */ | i2c_set_adapdata(i2c_imx-adapter, i2c_imx); | | /* Set up clock divider */ | if (pdata pdata-bitrate) | i2c_imx_set_clk(i2c_imx, pdata-bitrate); | else | i2c_imx_set_clk(i2c_imx, IMX_I2C_BIT_RATE); | | /* Set up chip registers to defaults */ | writeb(0, i2c_imx-base IMX_I2C_I2CR); | writeb(0, i2c_imx-base IMX_I2C_I2SR); | //添加adapter一个i2c对应一个adapter | /* Add I2C adapter */ | ret i2c_add_numbered_adapter(i2c_imx-adapter); ----------------- | if (ret 0) { | | dev_err(pdev-dev, registration failed\n); | | goto fail5; | | } | | | | /* Set up platform driver data */ | | platform_set_drvdata(pdev, i2c_imx); | | | | dev_dbg(i2c_imx-adapter.dev, claimed irq %d\n, i2c_imx-irq); | | dev_dbg(i2c_imx-adapter.dev, device resources from 0x%x to 0x%x\n,| | i2c_imx-res-start, i2c_imx-res-end); | | dev_dbg(i2c_imx-adapter.dev, allocated %d bytes at 0x%x \n, | | res_size, i2c_imx-res-start); | | dev_dbg(i2c_imx-adapter.dev, adapter name: \%s\\n, | | i2c_imx-adapter.name); | | dev_dbg(i2c_imx-adapter.dev, IMX I2C adapter registered\n); | | | | return 0; /* Return OK */ | | | |
fail5: | | free_irq(i2c_imx-irq, i2c_imx); | |
fail4: | | clk_put(i2c_imx-clk); | |
fail3: | | kfree(i2c_imx); | |
fail2: | | iounmap(base); | |
fail1: | | release_mem_region(res-start, resource_size(res)); | |
fail0: | | if (pdata pdata-exit) | | pdata-exit(pdev-dev); | | return ret; /* Return error number */ | |
} | || |
kernel/drivers/i2c/i2c-core.c | |
int i2c_add_numbered_adapter(struct i2c_adapter *adap) ---------- |
{ | int id; | int status; | | if (adap-nr ~MAX_ID_MASK) | return -EINVAL; | |
retry: | if (idr_pre_get(i2c_adapter_idr, GFP_KERNEL) 0) | return -ENOMEM; | | mutex_lock(core_lock); | /* above here means above or equal to, sigh; | * we need the equal to result to force the result | */ | status idr_get_new_above(i2c_adapter_idr, adap, adap-nr, id); | if (status 0 id ! adap-nr) { | status -EBUSY; | idr_remove(i2c_adapter_idr, id); | } | mutex_unlock(core_lock); | if (status -EAGAIN) | goto retry; | | if (status 0) | status i2c_register_adapter(adap); --------------- | return status; | |
} | |
EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter); | | | |
static int i2c_register_adapter(struct i2c_adapter *adap) -- |
{ | int res 0; | | /* Cant register until after driver model init */ | if (unlikely(WARN_ON(!i2c_bus_type.p))) { | res -EAGAIN; | goto out_list; | } | | /* Sanity checks */ | if (unlikely(adap-name[0] \0)) { | pr_err(i2c-core: Attempt to register an adapter with | no name!\n); | return -EINVAL; | } | if (unlikely(!adap-algo)) { | pr_err(i2c-core: Attempt to register adapter %s with | no algo!\n, adap-name); | return -EINVAL; | } | | rt_mutex_init(adap-bus_lock); | mutex_init(adap-userspace_clients_lock); | INIT_LIST_HEAD(adap-userspace_clients); | | /* Set default timeout to 1 second if not already set */ | if (adap-timeout 0) | adap-timeout HZ; | //设置设备名这里就是/dev显示的 /dev/i2c-1, /dev/i2c-2... | dev_set_name(adap-dev, i2c-%d, adap-nr); | adap-dev.bus i2c_bus_type; | adap-dev.type i2c_adapter_type; | res device_register(adap-dev); | if (res) | goto out_list; | | dev_dbg(adap-dev, adapter [%s] registered\n, adap-name); | |
#ifdef CONFIG_I2C_COMPAT | res class_compat_create_link(i2c_adapter_compat_class, adap-dev, | adap-dev.parent); | if (res) | dev_warn(adap-dev, | Failed to create compatibility class link\n); |
#endif | | /* create pre-declared device nodes */ | if (adap-nr __i2c_first_dynamic_bus_num) | i2c_scan_static_board_info(adap); | | /* Notify drivers */ | mutex_lock(core_lock); | bus_for_each_drv(i2c_bus_type, NULL, adap, __process_new_adapter); | mutex_unlock(core_lock); | | return 0; | |
out_list: | mutex_lock(core_lock); | idr_remove(i2c_adapter_idr, adap-nr); | mutex_unlock(core_lock); | return res; |
} |
kernel/driver/i2c/busses/i2c-imx.c |
static struct i2c_algorithm i2c_imx_algo { -------------------- .master_xfer i2c_imx_xfer, ----------------------------------.functionality i2c_imx_func, |
}; |
static u32 i2c_imx_func(struct i2c_adapter *adapter) |
{ |return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; |
} |
//发送接收会调用的函数 |
static int i2c_imx_xfer(struct i2c_adapter *adapter, ---------------------struct i2c_msg *msgs, int num) |
{ |unsigned int i, temp; |int result; |struct imx_i2c_struct *i2c_imx i2c_get_adapdata(adapter); ||dev_dbg(i2c_imx-adapter.dev, %s\n, __func__); ||/* Start I2C transfer */ |result i2c_imx_start(i2c_imx); |if (result) |goto fail0; ||/* read/write data */ |for (i 0; i num; i) { |if (i) { |dev_dbg(i2c_imx-adapter.dev, |%s repeated start\n, __func__); |temp readb(i2c_imx-base IMX_I2C_I2CR); |temp | I2CR_RSTA; |writeb(temp, i2c_imx-base IMX_I2C_I2CR); |result i2c_imx_bus_busy(i2c_imx, 1); |if (result) |goto fail0; |} |dev_dbg(i2c_imx-adapter.dev, |%s transfer message: %d\n, __func__, i); |/* write/read data */ |
#ifdef CONFIG_I2C_DEBUG_BUS |temp readb(i2c_imx-base IMX_I2C_I2CR); |dev_dbg(i2c_imx-adapter.dev, %s CONTROL: IEN%d, IIEN%d, |MSTA%d, MTX%d, TXAK%d, RSTA%d\n, __func__, |(temp I2CR_IEN ? 1 : 0), (temp I2CR_IIEN ? 1 : 0), |(temp I2CR_MSTA ? 1 : 0), (temp I2CR_MTX ? 1 : 0), |(temp I2CR_TXAK ? 1 : 0), (temp I2CR_RSTA ? 1 : 0)); |temp readb(i2c_imx-base IMX_I2C_I2SR); |dev_dbg(i2c_imx-adapter.dev, |%s STATUS: ICF%d, IAAS%d, IBB%d, |IAL%d, SRW%d, IIF%d, RXAK%d\n, __func__, |(temp I2SR_ICF ? 1 : 0), (temp I2SR_IAAS ? 1 : 0), |(temp I2SR_IBB ? 1 : 0), (temp I2SR_IAL ? 1 : 0), |(temp I2SR_SRW ? 1 : 0), (temp I2SR_IIF ? 1 : 0), |(temp I2SR_RXAK ? 1 : 0)); |
#endif |if (msgs[i].flags I2C_M_RD) |result i2c_imx_read(i2c_imx, msgs[i]); |else |result i2c_imx_write(i2c_imx, msgs[i]); |if (result) |goto fail0; |} ||
fail0: |/* Stop I2C transfer */ |i2c_imx_stop(i2c_imx); ||dev_dbg(i2c_imx-adapter.dev, %s exit with: %s: %d\n, __func__, |(result 0) ? error : success msg, |(result 0) ? result : num); |return (result 0) ? result : num; |
} ||
// i2c_msg记录了i2c地址 |
struct i2c_msg { |__u16 addr; /* slave address */ |__u16 flags; |
#define I2C_M_TEN 0x0010 /* this is a ten bit chip address */ |
#define I2C_M_RD 0x0001 /* read data, from slave to master */ |
#define I2C_M_NOSTART 0x4000 /* if I2C_FUNC_PROTOCOL_MANGLING */ |
#define I2C_M_REV_DIR_ADDR 0x2000 /* if I2C_FUNC_PROTOCOL_MANGLING */ |
#define I2C_M_IGNORE_NAK 0x1000 /* if I2C_FUNC_PROTOCOL_MANGLING */ |
#define I2C_M_NO_RD_ACK 0x0800 /* if I2C_FUNC_PROTOCOL_MANGLING */ |
#define I2C_M_RECV_LEN 0x0400 /* length will be first received byte */|__u16 len; /* msg length */ |__u8 *buf; /* pointer to msg data */ |
}; |||
3. 上层应用调用 |
kernel/driver/i2c/busses/i2c-dev.c |
static int __init i2c_dev_init(void) |
{ |int res; ||printk(KERN_INFO i2c /dev entries driver\n); ||res register_chrdev(I2C_MAJOR, i2c, i2cdev_fops); ------------ |if (res) | |goto out; | || |i2c_dev_class class_create(THIS_MODULE, i2c-dev); | |if (IS_ERR(i2c_dev_class)) { | |res PTR_ERR(i2c_dev_class); | |goto out_unreg_chrdev; | |} | || |/* Keep track of adapters which will be added or removed later */ | |res bus_register_notifier(i2c_bus_type, i2cdev_notifier); | |if (res) | |goto out_unreg_class; | || |/* Bind to already existing adapters right away */ | |i2c_for_each_dev(NULL, i2cdev_attach_adapter); | || |return 0; | || |
out_unreg_class: | |class_destroy(i2c_dev_class); | |
out_unreg_chrdev: | |unregister_chrdev(I2C_MAJOR, i2c); | |
out: | |printk(KERN_ERR %s: Driver Initialisation failed\n, __FILE__); | |return res; | |
} | |
static const struct file_operations i2cdev_fops { ------------- |.owner THIS_MODULE, |.llseek no_llseek, |.read i2cdev_read, ---------- |.write i2cdev_write, | |.unlocked_ioctl i2cdev_ioctl, | |.open i2cdev_open, | |.release i2cdev_release, | |
}; | |V |
static ssize_t i2cdev_read(struct file *file, char __user *buf, size_t count, |loff_t *offset) |
{ |char *tmp; |int ret; ||struct i2c_client *client file-private_data; ||if (count 8192) |count 8192; ||tmp kmalloc(count, GFP_KERNEL); |if (tmp NULL) |return -ENOMEM; ||pr_debug(i2c-dev: i2c-%d reading %zu bytes.\n, |iminor(file-f_path.dentry-d_inode), count); ||ret i2c_master_recv(client, tmp, count); --------------- |if (ret 0) | |ret copy_to_user(buf, tmp, count) ? -EFAULT : ret; | |kfree(tmp); | |return ret; | |
} | |V |
int i2c_master_recv(const struct i2c_client *client, char *buf, int count) |
{ |struct i2c_adapter *adap client-adapter; |struct i2c_msg msg; |int ret; ||msg.addr client-addr; //地址 | msg.flags client-flags I2C_M_TEN; //判断是否使用10位地址 | msg.flags | I2C_M_RD; //读操作 | msg.len count; //发送个数 | msg.buf buf; //发送数据 | |ret i2c_transfer(adap, msg, 1); --------------------------- || |/* If everything went ok (i.e. 1 msg transmitted), return #bytes | |transmitted, else error code. */ | |return (ret 1) ? count : ret; | |
} | || |
int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) -- |
{ |unsigned long orig_jiffies; |int ret, try; ||/* REVISIT the fault reporting model here is weak: |* |* - When we get an error after receiving N bytes from a slave, |* there is no way to report N. |* |* - When we get a NAK after transmitting N bytes to a slave, |* there is no way to report N ... or to let the master |* continue executing the rest of this combined message, if |* thats the appropriate response. |* |* - When for example num is two and we successfully complete |* the first message but get an error part way through the |* second, its unclear whether that should be reported as |* one (discarding status on the second message) or errno |* (discarding status on the first one). |*/ |//判断master_xfer函数指针是否存在存在的话就是指向i2c_imx_xfer |if (adap-algo-master_xfer) { -----------
#ifdef DEBUG |for (ret 0; ret num; ret) { |dev_dbg(adap-dev, master_xfer[%d] %c, addr0x%02x, |len%d%s\n, ret, (msgs[ret].flags I2C_M_RD) |? R : W, msgs[ret].addr, msgs[ret].len, |(msgs[ret].flags I2C_M_RECV_LEN) ? : ); |} |
#endif ||if (in_atomic() || irqs_disabled()) { |ret i2c_trylock_adapter(adap); |if (!ret) |/* I2C activity is ongoing. */ |return -EAGAIN; |} else { |i2c_lock_adapter(adap); |} ||/* Retry automatically on arbitration loss */ |orig_jiffies jiffies; |for (ret 0, try 0; try adap-retries; try) { |//调用 i2c_imx_xfer函数 | ret adap-algo-master_xfer(adap, msgs, num); ---------if (ret ! -EAGAIN) break; if (time_after(jiffies, orig_jiffies adap-timeout)) break; } i2c_unlock_adapter(adap); return ret; } else { dev_dbg(adap-dev, I2C level transfers not supported\n); return -EOPNOTSUPP; }
}
//同理write函数也是一样
static ssize_t i2cdev_write(struct file *file, const char __user *buf, size_t count, loff_t *offset)
{ int ret; char *tmp; struct i2c_client *client file-private_data; if (count 8192) count 8192; tmp memdup_user(buf, count); if (IS_ERR(tmp)) return PTR_ERR(tmp); pr_debug(i2c-dev: i2c-%d writing %zu bytes.\n, iminor(file-f_path.dentry-d_inode), count); ret i2c_master_send(client, tmp, count); ----------- kfree(tmp); | return ret; |
} | V
int i2c_master_send(const struct i2c_client *client, const char *buf, int count)
{ int ret; struct i2c_adapter *adap client-adapter; struct i2c_msg msg; msg.addr client-addr; msg.flags client-flags I2C_M_TEN; msg.len count; msg.buf (char *)buf; ret i2c_transfer(adap, msg, 1); /* If everything went ok (i.e. 1 msg transmitted), return #bytes transmitted, else error code. */ return (ret 1) ? count : ret;
} kernel/drivers/i2c/busses/i2c-imx.c
