Linux内核4.14版本——SPI框架（5）——spi device相关

目录

1. spi_add_device

1.1 spi_dev_set_name(设置bus id)

1.2 spi_setup（参数的一些默认设置和检查）

2. spi_alloc_device

---

1. spi_add_device

int spi_add_device(struct spi_device *spi)
{
	.....
	/* Chipselects are numbered 0..max; validate. */
	if (spi->chip_select >= ctlr->num_chipselect) {
		dev_err(dev, "cs%d >= max %d\n", spi->chip_select,
			ctlr->num_chipselect);
		return -EINVAL;
	}

	/* Set the bus ID string */
	spi_dev_set_name(spi);
	
	.......
	
	if (ctlr->cs_gpios)
		spi->cs_gpio = ctlr->cs_gpios[spi->chip_select];

	/* Drivers may modify this initial i/o setup, but will
	 * normally rely on the device being setup.  Devices
	 * using SPI_CS_HIGH can't coexist well otherwise...
	 */
	status = spi_setup(spi);
	......
	/* Device may be bound to an active driver when this returns */
	status = device_add(&spi->dev);
	......
}

1.1 spi_dev_set_name(设置bus id)

static void spi_dev_set_name(struct spi_device *spi)
{
	struct acpi_device *adev = ACPI_COMPANION(&spi->dev);

	if (adev) {
		dev_set_name(&spi->dev, "spi-%s", acpi_dev_name(adev));
		return;
	}

	dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->controller->dev),
		     spi->chip_select);
}

1.2 spi_setup（参数的一些默认设置和检查）

int spi_setup(struct spi_device *spi)
{
	unsigned	bad_bits, ugly_bits;
	int		status;

	/* check mode to prevent that DUAL and QUAD set at the same time
	 */
	if (((spi->mode & SPI_TX_DUAL) && (spi->mode & SPI_TX_QUAD)) ||
		((spi->mode & SPI_RX_DUAL) && (spi->mode & SPI_RX_QUAD))) {
		dev_err(&spi->dev,
		"setup: can not select dual and quad at the same time\n");
		return -EINVAL;
	}
	/* if it is SPI_3WIRE mode, DUAL and QUAD should be forbidden
	 */
	if ((spi->mode & SPI_3WIRE) && (spi->mode &
		(SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)))
		return -EINVAL;
	/* help drivers fail *cleanly* when they need options
	 * that aren't supported with their current controller
	 */
	bad_bits = spi->mode & ~spi->controller->mode_bits;
	ugly_bits = bad_bits &
		    (SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD);
	if (ugly_bits) {
		dev_warn(&spi->dev,
			 "setup: ignoring unsupported mode bits %x\n",
			 ugly_bits);
		spi->mode &= ~ugly_bits;
		bad_bits &= ~ugly_bits;
	}
	if (bad_bits) {
		dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
			bad_bits);
		return -EINVAL;
	}

	if (!spi->bits_per_word)
		spi->bits_per_word = 8;

	status = __spi_validate_bits_per_word(spi->controller,
					      spi->bits_per_word);
	if (status)
		return status;

	if (!spi->max_speed_hz)
		spi->max_speed_hz = spi->controller->max_speed_hz;

	if (spi->controller->setup)
		status = spi->controller->setup(spi);

	spi_set_cs(spi, false);

	dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s%u bits/w, %u Hz max --> %d\n",
			(int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
			(spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
			(spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
			(spi->mode & SPI_3WIRE) ? "3wire, " : "",
			(spi->mode & SPI_LOOP) ? "loopback, " : "",
			spi->bits_per_word, spi->max_speed_hz,
			status);

	return status;
}

（1）检查DUAL and QUAD是否同时存在

（2）如果是SPI_3WIRE，则禁止DUAL and QUAD

（3）如果spi->bits_per_word为0，默认设置为spi->bits_per_word = 8。

（4）设置默认的max_speed_hz

（5）调用spi->controller->setup

（6）片选选为非工作模式

2. spi_alloc_device

struct spi_device *spi_alloc_device(struct spi_controller *ctlr)
{
	struct spi_device	*spi;

	if (!spi_controller_get(ctlr))
		return NULL;

	spi = kzalloc(sizeof(*spi), GFP_KERNEL);
	if (!spi) {
		spi_controller_put(ctlr);
		return NULL;
	}

	spi->master = spi->controller = ctlr;
	spi->dev.parent = &ctlr->dev;
	spi->dev.bus = &spi_bus_type;
	spi->dev.release = spidev_release;
	spi->cs_gpio = -ENOENT;

	spin_lock_init(&spi->statistics.lock);

	device_initialize(&spi->dev);
	return spi;
}