Re: [PATCHv3 2/3] drivers: spi: Add qspi flash controller

[Nishanth Menon <nm@ti.com>]

On 19:12-20130708, Sourav Poddar wrote:
[..]
generic comment, given our historical mistakes of making drivers
specific to a SoC family, it never is.

Now, ti-qspi in file name is a step in the right direction, but, rest
of the code(function names etc) is just married to DRA7 family of
processor, when it should not be.

> diff --git a/drivers/spi/spi-ti-qspi.c b/drivers/spi/spi-ti-qspi.c
> new file mode 100644
> index 0000000..430de9c
> --- /dev/null
> +++ b/drivers/spi/spi-ti-qspi.c
[...]
> +static inline unsigned long dra7xxx_readl(struct dra7xxx_qspi *qspi,
> +		unsigned long reg)
> +{
> +	return readl(qspi->base + reg);
> +}
> +
> +static inline void dra7xxx_writel(struct dra7xxx_qspi *qspi,
> +		unsigned long val, unsigned long reg)
> +{
> +	writel(val, qspi->base + reg);
> +}
> +
> +static inline unsigned long dra7xxx_readl_data(struct dra7xxx_qspi *qspi,
> +		unsigned long reg, int wlen)
> +{
> +	switch (wlen) {
> +	case 8:
> +		return readw(qspi->base + reg);
> +		break;
> +	case 16:
> +		return readb(qspi->base + reg);
> +		break;
> +	case 32:
> +		return readl(qspi->base + reg);
> +		break;
> +	default:
> +		return -1;
> +	}
> +}
> +
> +static inline void dra7xxx_writel_data(struct dra7xxx_qspi *qspi,
> +		unsigned long val, unsigned long reg, int wlen)
> +{
> +	switch (wlen) {
> +	case 8:
> +		writew(val, qspi->base + reg);
> +		break;
> +	case 16:
> +		writeb(val, qspi->base + reg);
> +		break;
> +	case 32:
> +		writeb(val, qspi->base + reg);
> +		break;
> +	default:
> +		dev_dbg(qspi->dev, "word lenght out of range");
> +		break;
> +	}
> +}
Looks like a case to use regmap?
Dumb q: why cant we use regmap_spi? worst case, you should be able to
use mmio if regmap_spi cant be used. The commit message was not clear
about this.

> +
> +static int dra7xxx_qspi_setup(struct spi_device *spi)
> +{
> +	struct dra7xxx_qspi	*qspi = spi_master_get_devdata(spi->master);
> +	int clk_div = 0;
> +	u32 clk_ctrl_reg, clk_rate;
> +
> +	clk_rate = clk_get_rate(qspi->fclk);
> +
> +	if (!qspi->spi_max_frequency) {
> +		dev_err(qspi->dev, "spi max frequency not defined\n");
> +		return -1;
> +	} else
> +		clk_div = (clk_rate / qspi->spi_max_frequency) - 1;

did you run checkpatch --strict here?
Also, would you prefer to use DIV_ROUND_UP?

> +
> +	dev_dbg(qspi->dev, "%s: hz: %d, clock divider %d\n", __func__,
> +			qspi->spi_max_frequency, clk_div);
> +
> +	pm_runtime_get_sync(qspi->dev);
error check?
> +
> +	clk_ctrl_reg = dra7xxx_readl(qspi, QSPI_SPI_CLOCK_CNTRL_REG);
> +
> +	clk_ctrl_reg &= ~QSPI_CLK_EN;
> +
> +	/* disable SCLK */
> +	dra7xxx_writel(qspi, clk_ctrl_reg, QSPI_SPI_CLOCK_CNTRL_REG);
> +
> +	if (clk_div < 0) {
> +		dev_dbg(qspi->dev, "%s: clock divider < 0, using /1 divider\n",
> +				__func__);
> +		clk_div = 1;
should you not fail here?
> +	}
> +
> +	if (clk_div > QSPI_CLK_DIV_MAX) {
> +		dev_dbg(qspi->dev, "%s: clock divider >%d , using /%d divider\n",
> +			__func__, QSPI_CLK_DIV_MAX, QSPI_CLK_DIV_MAX + 1);
> +		clk_div = QSPI_CLK_DIV_MAX;
should you not fail here?
> +	}
> +
> +	/* enable SCLK */
> +	dra7xxx_writel(qspi, QSPI_CLK_EN | clk_div, QSPI_SPI_CLOCK_CNTRL_REG);
> +
> +	pm_runtime_mark_last_busy(qspi->dev);
> +	pm_runtime_put_autosuspend(qspi->dev);
error check?
> +
> +	return 0;
> +}
> +
> +static int dra7xxx_qspi_prepare_xfer(struct spi_master *master)
> +{
> +	struct dra7xxx_qspi *qspi = spi_master_get_devdata(master);
> +
> +	pm_runtime_get_sync(qspi->dev);
error check?
> +
> +	return 0;
> +}
> +
> +static int dra7xxx_qspi_unprepare_xfer(struct spi_master *master)
> +{
> +	struct dra7xxx_qspi *qspi = spi_master_get_devdata(master);
> +
> +	pm_runtime_mark_last_busy(qspi->dev);
> +	pm_runtime_put_autosuspend(qspi->dev);
error check?
> +
> +	return 0;
> +}
> +
> +static int qspi_write_msg(struct dra7xxx_qspi *qspi, struct spi_transfer *t)
> +{
> +	const u8 *txbuf;
> +	int wlen, count;
> +
> +	count = t->len;
> +	txbuf = t->tx_buf;
> +	wlen = t->bits_per_word;
> +
> +	while (count--) {
> +		dev_dbg(qspi->dev, "tx cmd %08x dc %08x data %02x\n",
> +			qspi->cmd | QSPI_WR_SNGL, qspi->dc, *txbuf);
> +		dra7xxx_writel(qspi, QSPI_WC_INT_EN, QSPI_INTR_ENABLE_SET_REG);
> +		dra7xxx_writel_data(qspi, *txbuf++, QSPI_SPI_DATA_REG, wlen);
> +		dra7xxx_writel(qspi, qspi->dc, QSPI_SPI_DC_REG);
> +		dra7xxx_writel(qspi, qspi->cmd | QSPI_WR_SNGL,
> +			QSPI_SPI_CMD_REG);
> +		wait_for_completion(&qspi->word_complete);
> +	}
> +
> +	return 0;
> +}
> +
> +static int qspi_read_msg(struct dra7xxx_qspi *qspi, struct spi_transfer *t)
> +{
> +	u8 *rxbuf;
> +	int wlen, count;
> +
> +	count = t->len;
> +	rxbuf = t->rx_buf;
> +	wlen = t->bits_per_word;
> +
> +	while (count--) {
> +		dev_dbg(qspi->dev, "rx cmd %08x dc %08x\n",
> +			qspi->cmd | QSPI_RD_SNGL, qspi->dc);
> +		dra7xxx_writel(qspi, QSPI_WC_INT_EN, QSPI_INTR_ENABLE_SET_REG);
> +		dra7xxx_writel(qspi, qspi->dc, QSPI_SPI_DC_REG);
> +		dra7xxx_writel(qspi, qspi->cmd | QSPI_RD_SNGL,
> +			QSPI_SPI_CMD_REG);
> +		wait_for_completion(&qspi->word_complete);
> +		*rxbuf++ = dra7xxx_readl_data(qspi, QSPI_SPI_DATA_REG, wlen);
*rxbuf =
> +		dev_dbg(qspi->dev, "rx done, read %02x\n", *(rxbuf-1));
rxbuf++ after dev_dbg?
> +	}
> +
> +	return 0;
> +}
> +
> +static int qspi_transfer_msg(struct dra7xxx_qspi *qspi, struct spi_transfer *t)
> +{
> +	if (t->tx_buf)
> +		qspi_write_msg(qspi, t);
what is the point of the function returning error when we dont use it?
> +	if (t->rx_buf)
> +		qspi_read_msg(qspi, t);
what is the point of the function returning error when we dont use it?
> +
> +	return 0;
> +}
> +
> +static int dra7xxx_qspi_start_transfer_one(struct spi_master *master,
> +		struct spi_message *m)
> +{
> +	struct dra7xxx_qspi *qspi = spi_master_get_devdata(master);
> +	struct spi_device *spi = m->spi;
> +	struct spi_transfer *t;
> +	int status = 0;
> +	int frame_length;
> +
> +	/* setup device control reg */
> +	qspi->dc = 0;
> +
> +	if (spi->mode & SPI_CPHA)
> +		qspi->dc |= QSPI_CKPHA(spi->chip_select);
> +	if (spi->mode & SPI_CPOL)
> +		qspi->dc |= QSPI_CKPOL(spi->chip_select);
> +	if (spi->mode & SPI_CS_HIGH)
> +		qspi->dc |= QSPI_CSPOL(spi->chip_select);
> +
> +	frame_length = DIV_ROUND_UP(m->frame_length * spi->bits_per_word,
> +				spi->bits_per_word);
> +
> +	frame_length = clamp(frame_length, 0, QSPI_FRAME_MAX);
> +
> +	/* setup command reg */
> +	qspi->cmd = 0;
> +	qspi->cmd |= QSPI_EN_CS(spi->chip_select);
> +	qspi->cmd |= QSPI_FLEN(frame_length);
> +
how does one ensure pm runtime has not disabled clocks in
background? e.g. long latency between transfers.
> +	list_for_each_entry(t, &m->transfers, transfer_list) {
> +		qspi->cmd |= QSPI_WLEN(t->bits_per_word);
> +		qspi->cmd |= QSPI_WC_CMD_INT_EN;
> +
> +		qspi_transfer_msg(qspi, t);
error handling?
> +
> +		m->actual_length += t->len;
> +
> +		if (list_is_last(&t->transfer_list, &m->transfers))
> +			goto out;
> +	}
> +
> +out:
> +	m->status = status;
> +	spi_finalize_current_message(master);
> +
> +	dra7xxx_writel(qspi, qspi->cmd | QSPI_INVAL, QSPI_SPI_CMD_REG);
> +
> +	return status;
> +}
> +
> +static irqreturn_t dra7xxx_qspi_isr(int irq, void *dev_id)
> +{
> +	struct dra7xxx_qspi *qspi = dev_id;
> +	u16 mask, stat;
> +
> +	irqreturn_t ret = IRQ_HANDLED;
> +
> +	spin_lock(&qspi->lock);
> +
what if autosuspend has triggered here? before ISR was scheduled?
> +	stat = dra7xxx_readl(qspi, QSPI_SPI_STATUS_REG);
> +	mask = dra7xxx_readl(qspi, QSPI_SPI_CMD_REG);
> +
> +	if ((stat & QSPI_WC) && (mask & QSPI_WC_CMD_INT_EN))
> +		ret = IRQ_WAKE_THREAD;
> +
> +	spin_unlock(&qspi->lock);
> +
> +	return ret;
> +}
> +
> +static irqreturn_t dra7xxx_qspi_threaded_isr(int this_irq, void *dev_id)
> +{
> +	struct dra7xxx_qspi *qspi = dev_id;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&qspi->lock, flags);
> +
what if autosuspend has triggered here? before ISR was scheduled?
> +	dra7xxx_writel(qspi, QSPI_WC_INT_DISABLE, QSPI_INTR_ENABLE_CLEAR_REG);
> +	dra7xxx_writel(qspi, QSPI_WC_INT_DISABLE,
> +			QSPI_INTR_STATUS_ENABLED_CLEAR);
> +
> +	complete(&qspi->word_complete);
> +
> +	spin_unlock_irqrestore(&qspi->lock, flags);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static const struct of_device_id dra7xxx_qspi_match[] = {
> +	{.compatible = "ti,dra7xxx-qspi" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, dra7xxx_qspi_match);
> +
> +static int dra7xxx_qspi_probe(struct platform_device *pdev)
> +{
> +	struct  dra7xxx_qspi *qspi;
> +	struct spi_master *master;
> +	struct resource         *r;
> +	struct device_node *np = pdev->dev.of_node;
> +	u32 max_freq;
> +	int ret = 0, num_cs, irq;
> +
> +	master = spi_alloc_master(&pdev->dev, sizeof(*qspi));
> +	if (!master)
> +		return -ENOMEM;
> +
> +	master->mode_bits = SPI_CPOL | SPI_CPHA;
> +
> +	master->num_chipselect = 1;
> +	master->bus_num = -1;
> +	master->setup = dra7xxx_qspi_setup;
> +	master->prepare_transfer_hardware = dra7xxx_qspi_prepare_xfer;
> +	master->transfer_one_message = dra7xxx_qspi_start_transfer_one;
> +	master->unprepare_transfer_hardware = dra7xxx_qspi_unprepare_xfer;
> +	master->dev.of_node = pdev->dev.of_node;
> +	master->bits_per_word_mask = BIT(32 - 1) | BIT(16 - 1) | BIT(8 - 1);
> +
> +	if (!of_property_read_u32(np, "ti,spi-num-cs", &num_cs))
> +		master->num_chipselect = num_cs;
> +
> +	platform_set_drvdata(pdev, master);
> +
> +	qspi = spi_master_get_devdata(master);
> +	qspi->master = master;
> +	qspi->dev = &pdev->dev;
> +
> +	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (r == NULL) {
> +		ret = -ENODEV;
> +		goto free_master;
> +	}
> +
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0) {
> +		dev_err(&pdev->dev, "no irq resource?\n");
> +		return irq;
> +	}
> +
> +	spin_lock_init(&qspi->lock);
> +
> +	qspi->base = devm_ioremap_resource(&pdev->dev, r);
> +	if (IS_ERR(qspi->base)) {
> +		ret = -ENOMEM;
> +		goto free_master;
> +	}
why not use devm_request_and_ioremap? Lock that region down so that no
two drivers can manage the same region?
> +
> +	ret = devm_request_threaded_irq(&pdev->dev, irq, dra7xxx_qspi_isr,
> +		dra7xxx_qspi_threaded_isr, IRQF_NO_SUSPEND | IRQF_ONESHOT,
> +			dev_name(&pdev->dev), qspi);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "Failed to register ISR for IRQ %d\n",
> +				irq);
> +		goto free_master;
> +	}
> +
> +	qspi->fclk = devm_clk_get(&pdev->dev, "fck");
> +	if (IS_ERR(qspi->fclk)) {
> +		ret = PTR_ERR(qspi->fclk);
> +		dev_err(&pdev->dev, "could not get clk: %d\n", ret);
> +	}
> +
> +	init_completion(&qspi->word_complete);
> +
> +	pm_runtime_use_autosuspend(&pdev->dev);
> +	pm_runtime_set_autosuspend_delay(&pdev->dev, SPI_AUTOSUSPEND_TIMEOUT);
> +	pm_runtime_enable(&pdev->dev);
> +
> +	if (!of_property_read_u32(np, "spi-max-frequency", &max_freq))
> +		qspi->spi_max_frequency = max_freq;
> +
> +	ret = spi_register_master(master);
> +	if (ret)
> +		goto free_master;
> +
> +	return ret;
> +
> +free_master:
> +	spi_master_put(master);
> +	return ret;
> +}
> +
> +static int dra7xxx_qspi_remove(struct platform_device *pdev)
> +{
> +	struct  dra7xxx_qspi *qspi = platform_get_drvdata(pdev);
> +
> +	spi_unregister_master(qspi->master);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver dra7xxx_qspi_driver = {
> +	.probe	= dra7xxx_qspi_probe,
> +	.remove	= dra7xxx_qspi_remove,
> +	.driver = {
> +		.name	= "ti,dra7xxx-qspi",
> +		.owner	= THIS_MODULE,
> +		.of_match_table = dra7xxx_qspi_match,
> +	}
no need for pm_ops?
> +};
> +
> +module_platform_driver(dra7xxx_qspi_driver);
> +
> +MODULE_LICENSE("GPL");
GPL V2?
> +MODULE_DESCRIPTION("TI QSPI controller driver");
MODULE_AUTHOR?
> -- 
> 1.7.1
> 
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-- 
Regards,
Nishanth Menon