一、SPI总线驱动介绍
SPI总线总共需要四根线,包括MOSI、MISO、CLK和CS。本文首先从SPI设备注册开始来讲述SPI总线驱动。
二、设备注册
在系统启动的时候,会按照顺序执行一些初始化程序,比如device_initcall和module_init等宏。这些宏是按照顺序执行的,
比如device_initcall的优先级高于module_init,现在我们看下在系统启动的时候注册的spi设备信息。
程序如下:
点击(此处)折叠或打开
- /* SPI controller
*/
- #if defined(CONFIG_GSC3280_SPI)
- #ifdef CONFIG_SPI1
- static struct resource spi1_resources[]
= {
- [0]
= {
- .start = GSC3280_SPI1_BASEADDR
& 0x1fffffff,
- .end =
(GSC3280_SPI1_BASEADDR
& 0x1fffffff)+ 0x54
- 1 ,
- .flags = IORESOURCE_MEM,
- },
- [1]
= {
- .start = EXT_GSC3280_SPI1_IRQ,
- .end = EXT_GSC3280_SPI1_IRQ,
- .flags = IORESOURCE_IRQ,
- },
-
};
- static struct platform_device gsc3280_spi1_device
= {
- .name =
"gsc3280-spi",
- .id = 1,
- #ifdef CONFIG_GSC3280_SPI_DMA
- .dev =
{
- .dma_mask =
NULL,
- .coherent_dma_mask = DMA_BIT_MASK(32),
- .platform_data =
NULL,
- },
- #endif
- .resource = spi1_resources,
- .num_resources = ARRAY_SIZE(spi1_resources),
-
};
- #endif
-
/* SPI devices
*/
- #if defined(CONFIG_SPI_FLASH_W25Q)
- static struct gsc3280_spi_info w25q_spi1_dev_platdata
= {
- .pin_cs = 87,
- .num_cs = 1,
- .cs_value = 0,
- .lsb_flg = 0,
- .bits_per_word = 8,
-
};
- #endif
- static struct spi_board_info gsc3280_spi_devices[]
= {
- #if defined(CONFIG_SPI_FLASH_W25Q)
- {
- .modalias =
"spi-w25q",
- .bus_num = 1,
- .chip_select = 3,
- .mode = SPI_MODE_3,
- .max_speed_hz = 5
* 1000 * 1000,
- .controller_data =
&w25q_spi1_dev_platdata,
- },
- #endif
-
};
- static int __init gsc3280_spi_devices_init(void)
-
{
- spi_register_board_info(gsc3280_spi_devices, ARRAY_SIZE(gsc3280_spi_devices));
- return 0;
-
}
- device_initcall(gsc3280_spi_devices_init);
- #endif //end #if defined(CONFIG_GSC3280_SPI)
点击(此处)折叠或打开
- int __init
- spi_register_board_info(struct spi_board_info const
*info, unsigned n)
- {
- struct boardinfo
*bi;
- int i;
- bi = kzalloc(n
* sizeof(*bi), GFP_KERNEL);
- if (!bi)
- return -ENOMEM;
- for (i
= 0; i
< n; i++, bi++,
info++) {
- struct spi_master
*master;
- memcpy(&bi->board_info, info,
sizeof(*info));
- mutex_lock(&board_lock);
- list_add_tail(&bi->list, &board_list);
- list_for_each_entry(master, &spi_master_list, list)
- spi_match_master_to_boardinfo(master, &bi->board_info);
- mutex_unlock(&board_lock);
- }
- return 0;
- }
对于此处,n为1,在程序中首先创建相应的内存,在for循环中,将信息保存到内存中,然后插入board_list链表,接着遍历
spi_master_list链表,注意此处,由于device_initcall的优先级高于module_init,所以此时spi_master_list链表为空,那么还
不能调用spi_match_master_to_boardinfo函数创建spi设备,具体的创建设备将在spi总线驱动的探测函数中,使用spi_register_master()
函数创建设备。
三、总线驱动探测、退出和电源管理函数
3.1、探测函数gsc3280_spi_probe
程序如下:
点击(此处)折叠或打开
- static int __init gsc3280_spi_probe(struct platform_device
*pdev)
-
{
- int ret = 0;
- struct gsc3280_spi *gscs;
- struct spi_master *master;
- struct resource *mem,
*ioarea;
- DBG("############\n");
- DBG("gsc3280 spi probe start\n");
- master = spi_alloc_master(&pdev->dev, sizeof(struct
gsc3280_spi));
- if (!master)
{
- ret =
-ENOMEM;
- DBG("!!!!spi_alloc_master error\n");
- goto exit;
- }
- gscs = spi_master_get_devdata(master);
- memset(gscs, 0, sizeof(struct gsc3280_spi));
- gscs->master
= spi_master_get(master);
- mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
- if (!mem)
{
- DBG("!!!!no mem resource!\n");
- ret =
-EINVAL;
- goto err_kfree;
- }
- ioarea = request_mem_region(mem->start, resource_size(mem),
pdev->name);
- if (!ioarea)
{
- DBG("!!!!SPI region already claimed!\n");
- ret =
-EBUSY;
- goto err_kfree;
- }
- gscs->regs
= ioremap_nocache(mem->start, resource_size(mem));
- if (!gscs->regs)
{
- DBG("!!!!SPI ioremap error!\n");
- ret =
-ENOMEM;
- goto err_release_reg;
- }
- DBG("gscs->regs = 0x%p\n", gscs->regs);
- gscs->irq
= platform_get_irq(pdev, 0);
- if (gscs->irq
< 0)
{
- DBG("!!!!no irq resource!\n");
- ret = gscs->irq;
- goto err_unmap;
- }
- ret = request_irq(gscs->irq, gsc3280_spi_irq,
IRQF_DISABLED, dev_name(&pdev->dev),
gscs);
- if (ret
< 0)
{
- DBG("!!!!can not get IRQ!\n");
- goto err_irq;
- }
- gscs->clk
= clk_get(NULL,
"spi1");
- if (IS_ERR(gscs->clk))
{
- DBG("!!!!failed to find spi1 clock source!\n");
- ret = PTR_ERR(gscs->clk);
- goto err_irq;
- }
- gscs->max_freq
= clk_get_rate(gscs->clk);
- DBG("rate is %d\n", gscs->max_freq);
- clk_enable(gscs->clk);
- gscs->bus_num
= pdev->id;
- gscs->num_cs
= 4;
- gscs->prev_chip
= NULL;
- INIT_LIST_HEAD(&gscs->queue);
- spin_lock_init(&gscs->slock);
-
- #ifdef CONFIG_GSC3280_SPI_DMA
- gscs->dma_priv
= pdev->dev.platform_data
= &spi_platform_data;
- if (!gscs->dma_priv)
- goto err_clk; //return
-ENOMEM;
- gscs->dma_ops
= &gscs_dma_ops;
- gscs->dma_inited
= 0;
- gscs->dma_addr
= (dma_addr_t)(gscs->regs
+ 0x24)
& 0x1fffffff;
- #endif
- platform_set_drvdata(pdev, master);
- master->mode_bits
= SPI_CPOL | SPI_CPHA;
- master->bus_num
= gscs->bus_num;
- master->num_chipselect
= gscs->num_cs;
- master->cleanup
= gsc3280_spi_cleanup;
- master->setup
= gsc3280_spi_setup;
- master->transfer
= gsc3280_spi_transfer;
- gsc3280_spi_hw_init(gscs);
- #ifdef CONFIG_SPI_GSC3280_DMA
- if (gscs->dma_ops
&& gscs->dma_ops->dma_init)
{
- ret = gscs->dma_ops->dma_init(gscs);
- if (ret)
{
- dev_warn(&master->dev,
"DMA init failed\n");
- gscs->dma_inited
= 0;
- }
- }
- #endif
- ret = gsc3280_init_queue(gscs);
- if (ret
!= 0)
{
- DBG("!!!!problem initializing queue!\n");
- goto err_diable_hw;
- }
- ret = gsc3280_start_queue(gscs);
- if (ret
!= 0)
{
- DBG("!!!!problem starting queue!\n");
- goto err_queue_alloc;
- }
- ret = spi_register_master(master);
- if (ret
!= 0)
{
- DBG("!!!!register spi master error!\n");
- goto err_queue_alloc;
- }
- DBG("gsc3280 spi probe success\n");
- DBG("############\n");
- return 0;
-
//err_free_master:
- //spi_master_put(master);
- err_queue_alloc:
- gsc3280_spi_destroy_queue(gscs);
- #ifdef CONFIG_SPI_GSC3280_DMA
- if (gscs->dma_ops
&& gscs->dma_ops->dma_exit)
- gscs->dma_ops->dma_exit(gscs);
- #endif
- err_diable_hw:
- gsc3280_enable_spi(gscs, GSC_SPI_DISABLE);
-
//err_clk:
- clk_disable(gscs->clk);
- clk_put(gscs->clk);
- err_irq:
- free_irq(gscs->irq, gscs);
- err_unmap:
- iounmap(gscs->regs);
- err_release_reg:
- release_mem_region(mem->start, resource_size(mem));
- err_kfree:
- kfree(gscs);
- kfree(master);
-
exit:
- printk(KERN_ERR
"!!!!!!gsc3280 probe error!!!!!!\n");
- return ret;
- }
1) 首先是总线资源的注册,包括申请IO空间和中断。
2) 接下来注册了中断函数。
3) 然后注册了spi_master所需要的函数,包括清除、设置和传输等函数,在四中会讲述。
4) gsc3280_spi_hw_init函数初始化了SPI总线寄存器,接下来讲述。
5) 总线驱动采用queue机制实现多设备SPI读写,接下来初始化和启动了queue,接下来讲述。
6) 使用spi_register_master函数注册master,此函数即实现创建了SPI设备结构体,接下来讲述。
SPI总线寄存器初始化函数gsc3280_spi_hw_init:
点击(此处)折叠或打开
- /* Restart the controller, disable all interrupts, clean fifo
*/
- static void gsc3280_spi_hw_init(struct gsc3280_spi
*gscs)
-
{
- gsc3280_enable_spi(gscs, GSC_SPI_DISABLE);
- gsc3280_spi_mask_intr(gscs, GSC_SPI_SR_MASK);
- if (!gscs->fifo_len)
{
- gscs->fifo_len
= 0x10;
- __raw_writew(0x00, gscs->regs
+ GSC_SPI_TXFTLR);
- __raw_writew(0x00, gscs->regs
+ GSC_SPI_RXFTLR);
- }
- gsc3280_enable_spi(gscs, GSC_SPI_ENABLE);
- }
由程序可以看出,此函数首先禁止SPI,屏蔽中断,然后设置fifo深度,最后使能SPI。
初始化queue函数gsc3280_init_queue:
点击(此处)折叠或打开
- static int __devinit gsc3280_init_queue(struct gsc3280_spi
*gscs)
-
{
- gscs->queue_state
= GSC_SPI_QUEUE_STOP;
- gscs->busy
= 0;
- tasklet_init(&gscs->pump_transfers, gsc3280_spi_pump_transfers,
(unsigned long)gscs);
- INIT_WORK(&gscs->pump_messages, gsc3280_spi_pump_messages);
- gscs->workqueue
= create_singlethread_workqueue(dev_name(gscs->master->dev.parent));
- if (gscs->workqueue
==
NULL) {
- DBG("!!!!create_singlethread_workqueue error!\n");
- return -EBUSY;
- }
- else
- return 0;
- }
开始queue函数gsc3280_start_queue:
点击(此处)折叠或打开
- static int gsc3280_start_queue(struct gsc3280_spi
*gscs)
-
{
- unsigned long flags;
- spin_lock_irqsave(&gscs->lock, flags);
- if ((gscs->run
== GSC_SPI_QUEUE_RUN)
|| gscs->busy)
{
- spin_unlock_irqrestore(&gscs->lock, flags);
- return -EBUSY;
- }
- gscs->run
= GSC_SPI_QUEUE_RUN;
- gscs->cur_msg
= NULL;
- gscs->cur_transfer
= NULL;
- gscs->cur_chip
= NULL;
- gscs->prev_chip
= NULL;
- spin_unlock_irqrestore(&gscs->lock, flags);
- queue_work(gscs->workqueue,
&gscs->pump_messages);
- return 0;
- }
此函数首先对queue的状态进行判断,然后初始化相关成员变量,最后调度queue。
最后看下master注册函数spi_register_master:
点击(此处)折叠或打开
- int spi_register_master(struct spi_master
*master)
-
{
- static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15)
- 1);
- struct device *dev
= master->dev.parent;
- struct boardinfo *bi;
- int status
= -ENODEV;
- int dynamic
= 0;
- if (!dev)
- return -ENODEV;
- /* even
if it‘s just one always-selected device, there must
- * be at least one chipselect
- */
- if (master->num_chipselect
== 0)
- return -EINVAL;
- /* convention: dynamically assigned bus IDs count down from the max
*/
- if (master->bus_num
< 0)
{
- /* FIXME switch
to an IDR based scheme, something like
- * I2C
now uses, so we can‘t run out of
"dynamic" IDs
- */
- master->bus_num
= atomic_dec_return(&dyn_bus_id);
- dynamic = 1;
- }
- spin_lock_init(&master->bus_lock_spinlock);
- mutex_init(&master->bus_lock_mutex);
- master->bus_lock_flag
= 0;
- /* register the device,
then userspace will see it.
- * registration fails
if the bus ID is
in use.
- */
- dev_set_name(&master->dev,
"spi%u", master->bus_num);
- status = device_add(&master->dev);
- if (status
< 0)
- goto done;
- dev_dbg(dev,
"registered master %s%s\n", dev_name(&master->dev),
- dynamic ?
" (dynamic)" :
"");
- mutex_lock(&board_lock);
- list_add_tail(&master->list,
&spi_master_list);
- list_for_each_entry(bi,
&board_list, list)
- spi_match_master_to_boardinfo(master,
&bi->board_info);
- mutex_unlock(&board_lock);
- status = 0;
- /* Register devices from the device tree
*/
- of_register_spi_devices(master);
- done:
- return status;
-
}
- EXPORT_SYMBOL_GPL(spi_register_master);
说明:
1) 首先对master成员变量进行检查。
2) 初始化成员变量。
3) 将master->list插入到spi_master_list链表中。
4) 语句list_for_each_entry(bi, &board_list, list)实现遍历board_list链表,在二设备注册中已经讲述了将设备插入到
board_list链表中。此时的board_list链表不为空,已经有相应设备结构体信息了。
5) 语句spi_match_master_to_boardinfo(master, &bi->board_info);实现设备的创建,函数程序如下:
点击(此处)折叠或打开
- static void spi_match_master_to_boardinfo(struct spi_master
*master,
- struct spi_board_info *bi)
-
{
- struct spi_device *dev;
- if (master->bus_num
!= bi->bus_num)
- return;
- dev = spi_new_device(master, bi);
- if (!dev)
- dev_err(master->dev.parent,
"can‘t create new device for %s\n",
- bi->modalias);
- }
说明:
1) 函数首先判断master的总线号和设备的总线号是否相等,如果不等直接返回。
2) 函数spi_new_device(master, bi);实现设备创建,如下:
点击(此处)折叠或打开
- struct spi_device *spi_new_device(struct spi_master
*master,
- struct spi_board_info *chip)
-
{
- struct spi_device *proxy;
- int status;
- /* NOTE: caller did any chip->bus_num checks necessary.
- *
- * Also, unless we change the return value convention
to use
- * error-or-pointer
(not
NULL-or-pointer), troubleshootability
- * suggests syslogged diagnostics are best here
(ugh).
- */
- proxy = spi_alloc_device(master);
- if (!proxy)
- return NULL;
- WARN_ON(strlen(chip->modalias)
>= sizeof(proxy->modalias));
- proxy->chip_select
= chip->chip_select;
- proxy->max_speed_hz
= chip->max_speed_hz;
- proxy->mode
= chip->mode;
- proxy->irq
= chip->irq;
- strlcpy(proxy->modalias, chip->modalias,
sizeof(proxy->modalias));
- proxy->dev.platform_data
= (void
*) chip->platform_data;
- proxy->controller_data
= chip->controller_data;
- proxy->controller_state
= NULL;
- status = spi_add_device(proxy);
- if (status
< 0)
{
- spi_dev_put(proxy);
- return NULL;
- }
- return proxy;
-
}
- EXPORT_SYMBOL_GPL(spi_new_device);
- struct spi_device *spi_alloc_device(struct spi_master
*master)
-
{
- struct spi_device *spi;
- struct device *dev
= master->dev.parent;
- if (!spi_master_get(master))
- return NULL;
- spi = kzalloc(sizeof
*spi, GFP_KERNEL);
- if (!spi)
{
- dev_err(dev,
"cannot alloc spi_device\n");
- spi_master_put(master);
- return NULL;
- }
- spi->master
= master;
- spi->dev.parent
= dev;
- spi->dev.bus
= &spi_bus_type;
- spi->dev.release
= spidev_release;
- device_initialize(&spi->dev);
- return spi;
-
}
- EXPORT_SYMBOL_GPL(spi_alloc_device);
说明:
1) 首先调用spi_alloc_device函数创建设备内存,从spi_alloc_device函数中可以看到,首先申请内存,然后对设备程序进行赋值。
2) 接下来将芯片的信息赋值给设备结构体,包括片选、最大速率、模式、中断和名称等。此处名称尤为重要,在spi设备的注册函数
spi_register_driver中,就是通过名称找到相应的设备信息结构体的。
3) 程序status = spi_add_device(proxy);实现添加spi设备信息。此函数在--Linux spi驱动分析(二)----spi内核中讲述。
3.2、移除函数gsc3280_spi_remove
程序如下:
点击(此处)折叠或打开
- void __exit gsc3280_spi_remove(struct platform_device
*pdev)
-
{
- int status
= 0;
- struct spi_master *master
= platform_get_drvdata(pdev);
- struct gsc3280_spi *gscs
= spi_master_get_devdata(master);
- if (!gscs)
- return;
- status = gsc3280_spi_destroy_queue(gscs);
- if (status
!= 0)
- dev_err(&gscs->master->dev,
"gsc3280_spi_remove: workqueue will not "
- "complete, message memory not freed\n");
- #ifdef CONFIG_SPI_GSC3280_DMA
- if (gscs->dma_ops
&& gscs->dma_ops->dma_exit)
- gscs->dma_ops->dma_exit(gscs);
- #endif
- gsc3280_enable_spi(gscs, GSC_SPI_DISABLE);
- free_irq(gscs->irq, gscs);
- iounmap(gscs->regs);
- spi_unregister_master(gscs->master);
- }
说明:
1) 首先获得总线结构体
2) 然后删除queue
3) 最后禁止SPI,释放中断和IO,最后注销master。
3.3、挂起函数gsc3280_spi_suspend
程序如下:
点击(此处)折叠或打开
- static int gsc3280_spi_suspend(struct platform_device
*pdev, pm_message_t mesg)
-
{
- int ret = 0;
- struct spi_master *master
= platform_get_drvdata(pdev);
- struct gsc3280_spi *gscs
= spi_master_get_devdata(master);
- ret = gsc3280_spi_stop_queue(gscs);
- if (ret)
- return ret;
- gsc3280_enable_spi(gscs, GSC_SPI_DISABLE);
- return ret;
- }
程序中首先停止queue,然后禁止SPI。
停止queue函数内容如下:
点击(此处)折叠或打开
- static int gsc3280_spi_stop_queue(struct gsc3280_spi
*gscs)
-
{
- int status
= 0;
- unsigned long flags;
- unsigned limit = 50;
-
- spin_lock_irqsave(&gscs->lock, flags);
- while ((!list_empty(&gscs->queue)
|| gscs->busy)
&& limit--)
{
- spin_unlock_irqrestore(&gscs->lock, flags);
- msleep(10);
- spin_lock_irqsave(&gscs->lock, flags);
- }
- if (!list_empty(&gscs->queue)
|| gscs->busy)
- status =
-EBUSY;
- else
- gscs->queue_state
= GSC_SPI_QUEUE_STOP;
- spin_unlock_irqrestore(&gscs->lock, flags);
- return status;
- }
程序首先遍历queue链表,查看是否还有queue没有执行,总共尝试50次,如果还有queue没有执行或者设备忙,则错误返回,否
则置正确queue状态。
3.4、恢复函数gsc3280_spi_resume
程序如下:
点击(此处)折叠或打开
- static int gsc3280_spi_resume(struct platform_device
*pdev)
-
{
- int ret = 0;
- struct spi_master *master
= platform_get_drvdata(pdev);
- struct gsc3280_spi *gscs
= spi_master_get_devdata(master);
- gsc3280_spi_hw_init(gscs);
- ret = gsc3280_start_queue(gscs);
- if (ret)
- dev_err(&gscs->master->dev,
"fail to start queue (%d)\n", ret);
- return ret;
- }
程序主要初始化SPI寄存器,然后开始运行queue。
四、spi master支持函数
4.1、清除函数gsc3280_spi_cleanup
点击(此处)折叠或打开
- static void gsc3280_spi_cleanup(struct spi_device
*spi)
-
{
- struct chip_data *chip
= spi_get_ctldata(spi);
- kfree(chip);
- }
程序首先获取设备指针,然后释放内存。
4.2、设置函数gsc3280_spi_setup
此函数是一个回调函数,spi核心中的spi_setup()函数会调用此函数,程序如下:
点击(此处)折叠或打开
- /* This may be called twice
for each spi dev
*/
- static int gsc3280_spi_setup(struct spi_device
*spi)
-
{
- int ret = 0;
- struct chip_data *chip
= NULL;
- struct gsc3280_spi_info *chip_info
= NULL;
- DBG("######gsc3280 spi bus setup start######\n");
- chip = spi_get_ctldata(spi); /*
Only alloc on first setup
*/
- if (!chip)
{
- chip = kzalloc(sizeof(struct chip_data), GFP_KERNEL);
- if (!chip)
{
- DBG("!!!!kzalloc error!\n");
- ret =
-ENOMEM;
- goto exit;
- }
- }
- chip_info = spi->controller_data;
- /* chip_info doesn‘t always exist
*/
- if (chip_info)
{
- #ifdef CONFIG_GSC3280_SPI_DMA
- chip->poll_mode
= chip_info->poll_mode;
- chip->enable_dma
= chip_info->enable_dma;
- #endif
- chip->pin_cs
= chip_info->pin_cs;
- chip->cs_value
= chip_info->cs_value;
- chip->bits_per_word
= chip_info->bits_per_word;
- chip->lsb_flg
= chip_info->lsb_flg;
- gpio_request(chip->pin_cs, spi->modalias);
- if (chip->cs_value
== 0)
- gpio_direction_output(chip->pin_cs, 1);
- else
- gpio_direction_output(chip->pin_cs, 0);
- }
- if (spi->bits_per_word
== 8)
{
- chip->n_bytes
= 1;
- #ifdef CONFIG_GSC3280_SPI_DMA
- chip->dma_width
= 1;
- #endif
- } else
if (spi->bits_per_word
== 16)
{
- chip->n_bytes
= 2;
- #ifdef CONFIG_GSC3280_SPI_DMA
- chip->dma_width
= 2;
- #endif
- } else
{
- DBG("!!!!spi->bits_per_word = %d error!\n", spi->bits_per_word);
- ret =
-EINVAL;
- goto exit;
- }
- if (!spi->max_speed_hz)
{
- DBG("!!!!spi->max_speed_hz = %d, error!\n", spi->max_speed_hz);
- ret =
-EINVAL;
- goto exit;
- }
- chip->speed_hz
= spi->max_speed_hz;
- chip->cr
= (chip->lsb_flg
<< GSC_SPI_CTL_BITS_NUM)
| (spi->mode
<< GSC_SPI_CTL_MOD)
- |
((chip->bits_per_word
- 1)
<< GSC_SPI_CTL_DSS);
- spi_set_ctldata(spi, chip);
-
exit:
- if (ret
!= 0)
- DBG("!!!!gsc3280 spi bus setup error!\n");
- else
- DBG("######gsc3280 spi bus setup success######\n");
- return ret;
- }
1) 首先判断参数,如果参数错误,直接返回。
2) 获取spi控制数据,如果没有,则申请内存创建设备。
3) 接下来根据实际情况对设备结构体赋值。
4.3、传输函数gsc3280_spi_transfer
此函数尤为重要,SPI设备传输数据时,就是调用此函数实现数据传输的,此函数主要完成结构体成员变量的
初始化,具体的传输在中断中进行。
点击(此处)折叠或打开
- /* spi driver
call this function transfer data
*/
- static int gsc3280_spi_transfer(struct spi_device
*spi, struct spi_message
*msg)
-
{
- unsigned long flags = 0;
- struct gsc3280_spi *gscs
= spi_master_get_devdata(spi->master);
- DBG("####gsc3280 spi transfer start####\n");
- if (gscs->queue_state
== GSC_SPI_QUEUE_STOP)
{
- DBG("!!!!queue is stop!\n");
- return -ESHUTDOWN;
- }
- msg->actual_length
= 0;
- msg->status
= -EINPROGRESS;
- msg->state
= START_STATE;
- spin_lock_irqsave(&gscs->slock, flags);
- list_add_tail(&msg->queue,
&gscs->queue);
- spin_unlock_irqrestore(&gscs->slock, flags);
- //writel(0x3f,
(volatile unsigned
int *)(0xbc04a000
+ 0x38)); //max divid freq
- if (gscs->cur_transfer
|| gscs->cur_msg)
{
- //DBG("gsc3280_spi_transfer: cur transfer or msg not empty\n");
- } else
{
- //DBG("gsc3280_spi_transfer: no cur transfer and msg\n");
- queue_work(gscs->workqueue,
&gscs->pump_messages);
- }
- DBG("####gsc3280 spi transfer success####\n");
- return 0;
- }
说明:
1) 首先判断queue状态,如果是停止状态,则退出。
2) 对传送结构体成员变量赋值。
3) 判断当前是否有数据在收发,如果有,就先直接返回。
4) 如果没有,则调用queue_work()函数,调度函数gsc3280_spi_pump_messages()。程序如下:
点击(此处)折叠或打开
- /*
- * when call this
function, no msg transfering
- * deal one msg when
call this funciton once.
- *
- */
- static void gsc3280_spi_pump_messages(struct work_struct
*work)
-
{
- unsigned long flags = 0;
- struct gsc3280_spi *gscs
= container_of(work, struct gsc3280_spi, pump_messages);
- DBG("####gsc3280_spi_pump_messages####\n");
- if (list_empty(&gscs->queue)
||
(gscs->queue_state
== GSC_SPI_QUEUE_STOP))
{
- if (gscs->queue_state
== GSC_SPI_QUEUE_STOP)
- DBG("!!!!queue is stop!\n");
- else
- DBG("msg is finished!\n");
- gscs->busy
= 0;
- return;
- }
-
- spin_lock_irqsave(&gscs->slock, flags);
- gscs->cur_msg
= list_entry(gscs->queue.next,
struct spi_message, queue);
- if (!gscs->cur_msg)
{
- spin_unlock_irqrestore(&gscs->slock, flags);
- DBG("!!!!gsc3280_spi_pump_messages: current no msg!\n");
- return;
- }
- list_del_init(&gscs->cur_msg->queue);
- gscs->cur_msg->state
= RUNNING_STATE;
- gscs->cur_chip
= spi_get_ctldata(gscs->cur_msg->spi);
- gscs->n_bytes
= gscs->cur_chip->n_bytes;
- gscs->busy
= 1;
- spin_unlock_irqrestore(&gscs->slock, flags);
- DBG("cs select enable\n");
- if (gscs->cur_chip->cs_value
== 0)
{
- gpio_set_value(gscs->cur_chip->pin_cs,
0);
- }
- else
- gpio_set_value(gscs->cur_chip->pin_cs,
1);
- /*
get first transfer */
- gscs->cur_transfer
= list_entry(gscs->cur_msg->transfers.next,
struct spi_transfer, transfer_list);
- if (!gscs->cur_transfer)
{
- DBG("!!!!gsc3280_spi_pump_transfers: current no transfer!\n");
- return;
- }
- tasklet_schedule(&gscs->pump_transfers);
- return;
- }
1) 此函数在两种情况下会被调用:
a) 当第一次开始SPI传输时,会调用此函数,设置message结构体变量。
b) 当传输完一个message后,如果判断还有message没有被传输,则调用此函数获取新的message。
2) 程序首先对变量进行检查,有两种退出情况,第一种是队列已经处于停止状态,第二种是传输msg链表为空。
3) 上锁,获取新的传输message,如果获取失败,直接解锁退出。
4) 如果获取msg成功,先删除获取成功msg的链表,然后对SPI总线驱动结构体变量赋初值。
5) 解锁,使能片选信号CS。
6) 获取传输的第一个transfer。
7) 调度gsc3280_spi_pump_transfers函数,函数如下:
点击(此处)折叠或打开
- /* when
call this function,the cur_msg
is the new msg */
- static void gsc3280_spi_pump_transfers(unsigned long data)
-
{
- int clk_div
= 0;
- u32 imask = 0, cr
= 0;
- unsigned long flags = 0;
- struct spi_transfer *previous
= NULL;
- struct gsc3280_spi *gscs
= (struct gsc3280_spi
*)data;
- //DBG("gsc3280_spi_pump_transfers\n");
- if (gscs->cur_msg->state
== ERROR_STATE)
{
- DBG("!!!!pump_transfers:cur msg state error!\n");
- gscs->cur_msg->status
= -EIO;
- goto early_exit;
- }
- /* Handle
end of message */
- if (gscs->cur_msg->state
== DONE_STATE)
{
- gscs->cur_msg->status
= 0;
- goto early_exit;
- }
- /* Delay
if requested at end of transfer*/
- if (gscs->cur_msg->state
== RUNNING_STATE)
{
- previous = list_entry(gscs->cur_transfer->transfer_list.prev,
struct spi_transfer, transfer_list);
- if (previous->delay_usecs)
- udelay(previous->delay_usecs);
- }
- #ifdef CONFIG_SPI_GSC3280_DMA
- gscs->dma_width
= gscs->cur_chip->dma_width;
- gscs->rx_dma
= gscs->cur_transfer->rx_dma;
- gscs->tx_dma
= gscs->cur_transfer->tx_dma;
- #endif
- /* Handle per transfer options
for bpw and speed
*/
- if (gscs->cur_transfer->speed_hz)
{
- if (gscs->cur_transfer->speed_hz
!= gscs->cur_chip->speed_hz)
{
- if
(gscs->cur_transfer->speed_hz
> gscs->max_freq)
{
- printk(KERN_ERR
"SPI1: unsupported freq: %dHz\n", gscs->cur_transfer->speed_hz);
- gscs->cur_msg->status
= -EIO;
- return;
- }
else
- gscs->cur_chip->speed_hz
= gscs->cur_transfer->speed_hz;
- }
- }
- if (gscs->cur_transfer->bits_per_word)
{
- switch (gscs->cur_transfer->bits_per_word)
{
- case 8:
- case 16:
- gscs->n_bytes
= gscs->cur_transfer->bits_per_word
>> 3;
- #ifdef CONFIG_SPI_GSC3280_DMA
- gscs->dma_width
= gscs->n_bytes;
- #endif
- break;
- default:
- printk(KERN_ERR
"SPI1: unsupported bits:" "%db\n", gscs->cur_transfer->bits_per_word);
- gscs->cur_msg->status
= -EIO;
- return;
- }
- }
- clk_div = gscs->max_freq
/ gscs->cur_transfer->speed_hz;
- clk_div = clk_div
/ 2 - 1;
- if (clk_div
< 0)
- clk_div = 0;
- gscs->cur_chip->clk_div
= (u16)clk_div;
- cr = gscs->cur_chip->cr
| GSC_SPI_CTL_EN;
- writel(cr, gscs->regs
+ GSC_SPI_CTRL); /* enable spi
*/
- writel(gscs->cur_chip->clk_div, gscs->regs
+ GSC_SPI_SEABAUR);
-
- spin_lock_irqsave(&gscs->slock, flags);
- //gscs->n_bytes
= gscs->cur_chip->n_bytes;
- gscs->tx
= (void
*)gscs->cur_transfer->tx_buf;
- gscs->tx_end
= gscs->tx
+ gscs->cur_transfer->len;
- gscs->rx
= gscs->cur_transfer->rx_buf;
- gscs->rx_end
= gscs->rx
+ gscs->cur_transfer->len;
- gscs->cs_change
= gscs->cur_transfer->cs_change;
- gscs->len
= gscs->cur_transfer->len;
- spin_unlock_irqrestore(&gscs->slock, flags);
-
- imask |= SPI_INT_TX_H_OVER
| SPI_INT_RX_L_OVER
| SPI_INT_RX_H_OVER | SPI_INT_RX_FULL;
- if (gscs->tx
!=
NULL) {
- imask |= SPI_INT_TX_EMPTY;
- }
- gsc3280_spi_umask_intr(gscs, imask);
- #ifdef CONFIG_GSC3280_SPI_DMA
- /* Check
if current transfer
is a DMA transaction */
- gscs->dma_mapped
= map_dma_buffers(gscs);
- /* Interrupt mode we only need
set the TXEI IRQ, as TX/RX always happen syncronizely
*/
- if (!gscs->dma_mapped
&&
!gscs->cur_chip->poll_mode)
{
- //int templen
= gscs->len
/ gscs->n_bytes;
- //txint_level
= gscs->fifo_len
/ 2;
- //txint_level
= (templen
> txint_level)
? txint_level : templen;
- }
- if (gscs->dma_mapped)
- gscs->dma_ops->dma_transfer(gscs, cs_change);
- if (gscs->cur_chip->poll_mode)
- gsc3280_spi_poll_transfer(gscs);
- #endif
-
- return;
-
- early_exit:
- gsc3280_spi_giveback(gscs);
- return;
- }
1) 首先对msg变量进行检测。
2) 如果变量正确,获取此次传输的分频系数和每次传输几个字节。
3) 设置SPI控制寄存器和分频寄存器,
4) 设置SPI总线驱动结构体中的传输或者接收数据指针,打开中断,开始数据传输。
5) 每传输一个transfer,都会调用此函数一次。
实际的传输数据在中断中进行,程序如下:
点击(此处)折叠或打开
- /* this
is transfer message
function */
- static irqreturn_t gsc3280_spi_irq(int irq, void
*dev_id)
-
{
- struct gsc3280_spi *gscs
= dev_id;
- u32 irq_status = __raw_readw(gscs->regs
+ GSC_SPI_ISR);
-
- //DBG("gsc3280_spi_irq\n");
- //DBG("sys_ctl0 = 0x%x\n", readl((volatile
unsigned int *)(0xbc04a000
+ 0x08)));
- //DBG("clddiv_spi1 = 0x%x\n", readl((volatile
unsigned int *)(0xbc04a000
+ 0x38)));
- //DBG("imux_cfg0 = 0x%x\n", readl((volatile
unsigned int *)(0xbc04a000
+ 0xb0)));
- DBG("cr = 0x%x\n", __raw_readw(gscs->regs
+ GSC_SPI_CTRL));
- DBG("imsr = 0x%x, irq_status = 0x%x\n", __raw_readl(gscs->regs
+ GSC_SPI_IMSR), irq_status);
- if (!irq_status
) {
- DBG("!!!!gsc3280_spi_irq: no irq!\n");
- return IRQ_NONE;
- }
- if (!gscs->cur_msg)
{
- DBG("!!!!gsc3280_spi_irq: no msg!\n");
- gsc3280_spi_mask_intr(gscs, SPI_INT_TX_EMPTY
| SPI_INT_RX_FULL);
- return IRQ_HANDLED;
- }
- if (irq_status
& (SPI_INT_TX_H_OVER
| SPI_INT_RX_L_OVER
| SPI_INT_RX_H_OVER))
{
- DBG("!!!!gsc3280_spi_irq: fifo overrun/underrun!\n");
- __raw_writew(0x0e, gscs->regs
+ GSC_SPI_ISR);
- gscs->cur_msg->state
= ERROR_STATE;
- gscs->cur_msg->status
= -EIO;
- queue_work(gscs->workqueue,
&gscs->pump_messages);
- return IRQ_HANDLED;
- }
- if (irq_status
& SPI_INT_RX_FULL)
{
- spi_gsc_read(gscs);
- return IRQ_HANDLED;
- }
- if (irq_status
& SPI_INT_TX_EMPTY)
{
- spi_gsc_write(gscs);
- }
- return IRQ_HANDLED;
- }
1) 首先读取中断状态,如果是空中断,退出中断。
2) 判断当前是否有msg在传输,如果没有,退出中断。
3) 判断是否是错误中断,包括溢出等,如果是,屏蔽中断,退出中断。
4) 如果是接收满中断,则首先接收数据。然后退出中断。
4) 如果是发送空中断,则发送数据,发送完成后,退出中断。
现在看下发送数据函数spi_gsc_write():
点击(此处)折叠或打开
- static void gsc3280_writer(struct gsc3280_spi
*gscs)
-
{
- u16 txw = 0;
- unsigned long flags = 0;
- u32 max = gsc3280_spi_tx_max(gscs);
- //DBG("max = %d, gscs->n_bytes = 0x%x", max,
gscs->n_bytes);
- spin_lock_irqsave(&gscs->slock, flags);
- while (max--)
{
- if (gscs->n_bytes
== 1)
- txw =
*(u8 *)(gscs->tx);
- else
- txw =
*(u16 *)(gscs->tx);
- DBG("txw = 0x%x\n", txw);
- writel(txw, gscs->regs
+ GSC_SPI_DA_S);
- gscs->tx
+= gscs->n_bytes;
- }
- spin_unlock_irqrestore(&gscs->slock, flags);
-
}
- static void spi_gsc_write(struct gsc3280_spi
*gscs)
-
{
- //DBG("spi_gsc_write\n");
- gsc3280_spi_mask_intr(gscs, GSC_SPI_SR_MASK);
- gsc3280_writer(gscs);
- if (gscs->tx_end
== gscs->tx)
{
- gsc3280_spi_xfer_done(gscs);
- }
- else {
- gsc3280_spi_umask_intr(gscs, GSC_SPI_SR_MASK);
- }
- }
说明:
1) 首先屏蔽中断。
2) 发送数据。
3) 如果发送完成,执行gsc3280_spi_xfer_done(gscs)函数。
4) 如果没有完成,打开中断,继续发数据。
对于gsc3280_spi_xfer_done()函数,如下:
点击(此处)折叠或打开
- static void *gsc3280_spi_next_transfer(struct gsc3280_spi
*gscs)
-
{
- struct spi_message *msg
= gscs->cur_msg;
- struct spi_transfer *trans
= gscs->cur_transfer;
- if (trans->transfer_list.next
!=
&msg->transfers)
{
- gscs->cur_transfer
= list_entry(trans->transfer_list.next,
struct spi_transfer, transfer_list);
- return RUNNING_STATE;
- } else
- return DONE_STATE;
-
}
- static void gsc3280_spi_xfer_done(struct gsc3280_spi
*gscs)
-
{
- //DBG("gsc3280_spi_xfer_done\n");
- //DBG("irq_status = 0x%x\n", __raw_readw(gscs->regs
+ GSC_SPI_ISR));
- //DBG("imsr = 0x%x\n", __raw_readl(gscs->regs
+ GSC_SPI_IMSR));
- /* Update total byte transferred return count actual bytes read
*/
- gscs->cur_msg->actual_length
+= gscs->len;
- /* Move
to next transfer
*/
- gscs->cur_msg->state
= gsc3280_spi_next_transfer(gscs);
- if (gscs->cur_msg->state
== DONE_STATE)
{
- /* Handle
end of message */
- gscs->cur_msg->status
= 0;
- gsc3280_spi_giveback(gscs);
- } else
{
- tasklet_schedule(&gscs->pump_transfers);
- }
-
} 说明:
1) 获取下一个transfer,如果还有,则调度gsc3280_spi_pump_transfers()函数准备开始传输。
2) 如果没有transfer需要传输,调用函数gsc3280_spi_giveback(gscs),说明此时已经处理完成了一个msg。
gsc3280_spi_giveback(gscs)函数如下:
点击(此处)折叠或打开
- /* Caller already
set message->status; dma
and pio irqs are blocked
*/
- static void gsc3280_spi_giveback(struct gsc3280_spi
*gscs)
-
{
- unsigned long flags = 0;
- DBG("gsc3280_spi_giveback\n");
- //DBG("irq_status = 0x%x\n", readl(gscs->regs
+ GSC_SPI_ISR));
- gsc3280_spi_mask_intr(gscs, GSC_SPI_SR_MASK);
- DBG("cs select disable\n");
- if (gscs->cur_chip->cs_value
== 0)
{
- gpio_set_value(gscs->cur_chip->pin_cs,
1);
- }
- else
- gpio_set_value(gscs->cur_chip->pin_cs,
0);
- gscs->cur_msg->state
= NULL;
- if (gscs->cur_msg->complete)
- gscs->cur_msg->complete(gscs->cur_msg->context);
-
- spin_lock_irqsave(&gscs->slock, flags);
- gscs->cur_msg
= NULL;
- gscs->cur_transfer
= NULL;
- gscs->prev_chip
= gscs->cur_chip;
- gscs->cur_chip
= NULL;
- gscs->busy
= 0;
- #ifdef CONFIG_SPI_GSC3280_DMA
- gscs->dma_mapped
= 0;
- #endif
- spin_unlock_irqrestore(&gscs->slock, flags);
- queue_work(gscs->workqueue,
&gscs->pump_messages);
- }
说明:
1) 首先屏蔽中断。
2) 禁止片选。
3) 设置完成msg。
4) 上锁,初始化SPI总线结构体变量。
5) 调用gsc3280_spi_pump_messages()函数,处理下一个msg。
中断接收数据函数spi_gsc_read(gscs)如下:
点击(此处)折叠或打开
- static void gsc3280_reader(struct gsc3280_spi
*gscs)
-
{
- u16 rxw = 0;
- unsigned long flags = 0;
- u32 max = gsc3280_spi_rx_max(gscs);
- //DBG("max = %d, gscs->n_bytes = 0x%x", max,
gscs->n_bytes);
- spin_lock_irqsave(&gscs->slock, flags);
- while (max--)
{
- rxw = readl(gscs->regs
+ GSC_SPI_DA_S);
- DBG("rxw = 0x%x\n", rxw);
- if (gscs->n_bytes
== 1)
- *(u8
*)(gscs->rx)
= (u8)rxw;
- else
- *(u16
*)(gscs->rx)
= rxw;
- gscs->rx
+= gscs->n_bytes;
- }
- spin_unlock_irqrestore(&gscs->slock, flags);
-
}
- static void spi_gsc_read(struct gsc3280_spi
*gscs)
-
{
- //DBG("spi_gsc_read\n");
- gsc3280_reader(gscs);
- if (gscs->rx_end
== gscs->rx)
{
- gsc3280_spi_xfer_done(gscs);
- }
- }
说明:
1) 首先接收数据,如果接收成功,调用gsc3280_spi_xfer_done(gscs);。
到此,SPI总线驱动就全部讲述完成了,在总线驱动中,使用了queue和tasklet两种机制,queue实现了不同
msg的传输,tasklet实现了msg中不同transfer的传输。