新内核 中关于spi nor的注册

3.X的内核,对于platform_device的注册和platform data,全都放在dts文件中指定,对于spi nor来说,它的整个驱动

包括了master  driver,master device,spi nor driver 和spi nor device.

对于spi master的驱动是在driver/spi/下有相关的文件来完成,而spi master device是在dts中来指定,

对于zynq板子来说,我们在driver/spi/可以找到相关的spi master的驱动文件,在这里它就是一个platfrom driver.

对于device 是在dts文件中一指定的:

 ps7_qspi_0: ps7-qspi@e000d000 {

   clock-names = "ref_clk", "aper_clk";

   clocks = <&clkc 10>, <&clkc 43>;

   compatible = "xlnx,zynq-qspi-1.0";

   interrupt-parent = <&ps7_scugic_0>;

   interrupts = <0 19 4>;

   is-dual = <0>;

   num-chip-select = <1>;

   reg = <0xe000d000 0x1000>;

   xlnx,fb-clk = <0x1>;

   xlnx,qspi-mode = <0x0>;

   #address-cells = <1>;

   #size-cells = <0>;

   flash@0 {

    compatible = "s25fl256s1";

    reg = <0x0>;

    spi-max-frequency = <50000000>;

    #address-cells = <1>;

    #size-cells = <1>;

    partition@qspi-fsbl-uboot {

     label = "qspi-fsbl-uboot";

     reg = <0x0 0x100000>;

    };

    partition@qspi-linux {

     label = "qspi-linux";

     reg = <0x100000 0x500000>;

    };

    partition@qspi-device-tree {

     label = "qspi-device-tree";

     reg = <0x600000 0x20000>;

    };

    partition@qspi-rootfs {

     label = "qspi-rootfs";

     reg = <0x620000 0x5E0000>;

    };

    partition@qspi-bitstream {

     label = "qspi-bitstream";

     reg = <0xC00000 0x400000>;

    };

   };

  } ;

在linux启动后,会解析这个dts文件,当进行spi master driver注册时,会进行match,之后就调用spi master driver下的probe函数,

probe函数中会调用spi_register_master函数.我们知道有spi master只是有总线的驱动了,那一定还有spi相关的device,没错,

spi device就是在spi_register_master中来完成的,我们也可以通过上面的spi master 的dts代码看到,在这个spi bus 下只挂了一个spi nor flash.在spi_register_master中会对master下所挂的spi nor device进行add:

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;

 status = of_spi_register_master(master);

 if (status)

  return status;

 /* even if it's just one always-selected device, there must

  * be at least one chipselect

  */

 if (master->num_chipselect == 0)

  return -EINVAL;

 if ((master->bus_num < 0) && master->dev.of_node)

  master->bus_num = of_alias_get_id(master->dev.of_node, "spi");

 /* 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;

 init_completion(&master->xfer_completion);

 if (!master->max_dma_len)

  master->max_dma_len = INT_MAX;

 /* 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)" : "");

 /* If we're using a queued driver, start the queue */

 if (master->transfer)

  dev_info(dev, "master is unqueued, this is deprecated\n");

 else {

  status = spi_master_initialize_queue(master);

  if (status) {

   device_del(&master->dev);

   goto done;

  }

 }

 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);

 /* Register devices from the device tree and ACPI */

 of_register_spi_devices(master); //注册这个master下所挂载的spi device.

 acpi_register_spi_devices(master);

done:

 return status;

}

static void of_register_spi_devices(struct spi_master *master)

{

 struct spi_device *spi;

 struct device_node *nc;

 int rc;

 u32 value;

 if (!master->dev.of_node)

  return;

 for_each_available_child_of_node(master->dev.of_node, nc) {

  /* Alloc an spi_device */

  spi = spi_alloc_device(master);

  if (!spi) {

   dev_err(&master->dev, "spi_device alloc error for %s\n",

    nc->full_name);

   spi_dev_put(spi);

   continue;

  }

  /* Select device driver */

  if (of_modalias_node(nc, spi->modalias,

         sizeof(spi->modalias)) < 0) {

   dev_err(&master->dev, "cannot find modalias for %s\n",

    nc->full_name);

   spi_dev_put(spi);

   continue;

  }

  /* Device address */

  rc = of_property_read_u32(nc, "reg", &value);

  if (rc) {

   dev_err(&master->dev, "%s has no valid 'reg' property (%d)\n",

    nc->full_name, rc);

   spi_dev_put(spi);

   continue;

  }

  spi->chip_select = value;

  /* Mode (clock phase/polarity/etc.) */

  if (of_find_property(nc, "spi-cpha", NULL))

   spi->mode |= SPI_CPHA;

  if (of_find_property(nc, "spi-cpol", NULL))

   spi->mode |= SPI_CPOL;

  if (of_find_property(nc, "spi-cs-high", NULL))

   spi->mode |= SPI_CS_HIGH;

  if (of_find_property(nc, "spi-3wire", NULL))

   spi->mode |= SPI_3WIRE;

  if (of_find_property(nc, "spi-lsb-first", NULL))

   spi->mode |= SPI_LSB_FIRST;

  /* Device DUAL/QUAD mode */

   if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) { //从dts中获取相关的写模式,

   switch (value) {

   case 1:

    break;

   case 2:

    spi->mode |= SPI_TX_DUAL;

    break;

   case 4:

    spi->mode |= SPI_TX_QUAD;

    break;

   default:

    dev_warn(&master->dev,

      "spi-tx-bus-width %d not supported\n",

      value);

    break;

   }

  }

    if (!of_property_read_u32(nc, "spi-rx-bus-width", &value)) { //获取read的mode

   switch (value) {

   case 1:

    break;

   case 2:

    spi->mode |= SPI_RX_DUAL;

    break;

   case 4:

    spi->mode |= SPI_RX_QUAD;

    break;

   default:

    dev_warn(&master->dev,

      "spi-rx-bus-width %d not supported\n",

      value);

    break;

   }

  }

  /* Device speed */

  rc = of_property_read_u32(nc, "spi-max-frequency", &value);

  if (rc) {

   dev_err(&master->dev, "%s has no valid 'spi-max-frequency' property (%d)\n",

    nc->full_name, rc);

   spi_dev_put(spi);

   continue;

  }

  spi->max_speed_hz = value;

  /* IRQ */

  spi->irq = irq_of_parse_and_map(nc, 0);

  /* Store a pointer to the node in the device structure */

  of_node_get(nc);

  spi->dev.of_node = nc;

  /* Register the new device */

  request_module("%s%s", SPI_MODULE_PREFIX, spi->modalias); //加载设备对应的驱动文件

  rc = spi_add_device(spi); //增加这个spi device

  if (rc) {

   dev_err(&master->dev, "spi_device register error %s\n",

    nc->full_name);

   spi_dev_put(spi);

  }

 }

}

我们可以看到在这个函数中完成了相关spi device的增加和相关属性的指定.

但在这些代码中我们没有找到相关partition的指定,因为partition在spi nor driver的probe中会从spi device中的platfrom_data中直接获取.????如下,也有可能是在解析dts时就已经对device中的platform_data作了指定.可以看最后面的备注.

static int m25p_probe(struct spi_device *spi)

{

 struct mtd_part_parser_data ppdata;

 struct flash_platform_data *data;

 struct m25p *flash;

 struct spi_nor *nor;

 enum read_mode mode = SPI_NOR_NORMAL;

 int ret;

 flash = devm_kzalloc(&spi->dev, sizeof(*flash), GFP_KERNEL);

 if (!flash)

  return -ENOMEM;

 nor = &flash->spi_nor;

 /* install the hooks */

 nor->read = m25p80_read;

 nor->write = m25p80_write;

 nor->erase = m25p80_erase;

 nor->write_reg = m25p80_write_reg;

 nor->read_reg = m25p80_read_reg;

 nor->dev = &spi->dev;

 nor->mtd = &flash->mtd;

 nor->priv = flash;

 spi_set_drvdata(spi, flash);

 flash->mtd.priv = nor;

 flash->spi = spi;

 if (spi->mode & SPI_RX_QUAD)

  mode = SPI_NOR_QUAD;

 else if (spi->mode & SPI_RX_DUAL)

  mode = SPI_NOR_DUAL;

 ret = spi_nor_scan(nor, spi_get_device_id(spi), mode);

 if (ret)

  return ret;

  data = dev_get_platdata(&spi->dev); //获取device platform_data

 ppdata.of_node = spi->dev.of_node;

  return mtd_device_parse_register(&flash->mtd, NULL, &ppdata,

   data ? data->parts : NULL,

   data ? data->nr_parts : 0);

}

注:

系统平台上挂载了很多总线，如i2c、spi、uart等等，每一个总线分别被描述为一个节点。Linux在启动后，到C入口时，会执行以下操作，加载系统平台上的总线和设备：

start_kernel() --> setup_arch() --> unflatten_device_tree() .

在执行完unflatten_device_tree()后，DTS节点信息被解析出来，保存到of_allnodes链表中，of_allnodes会在后面被用到。

随后，当系统启动到board文件时，会调用.init_machine，高通zynq平台对应的是zynq_init_machine()。接着调用of_platform_populate(....)接口，加载平台总线和平台设备。至此，系统平台上的所有已配置的总线和设备将被注册到系统中。

在of_platform_populate会调用of_platform_bus_create函数,在这里面会地我上面所提到platform_data进行指定:of_platform_device_create_pdata.