Date:	Mon, 8 Jul 2013 17:32:51 +0300
From:	Felipe Balbi <balbi@...com>
To:	Sourav Poddar <sourav.poddar@...com>
CC:	<broonie@...nel.org>, <spi-devel-general@...ts.sourceforge.net>,
	<grant.likely@...aro.org>, <balbi@...com>, <rnayak@...com>,
	<linux-omap@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv3 2/3] drivers: spi: Add qspi flash controller

Hi,

On Mon, Jul 08, 2013 at 07:12:59PM +0530, Sourav Poddar wrote:
> +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;

return -EINVAL ? or some other error code ?

> +	}
> +}
> +
> +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;
> +	}
> +}
> +
> +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;

same here

> +	} else

this needs to have curly braces too, per CodingStyle

> +		clk_div = (clk_rate / qspi->spi_max_frequency) - 1;
> +
> +	dev_dbg(qspi->dev, "%s: hz: %d, clock divider %d\n", __func__,
> +			qspi->spi_max_frequency, clk_div);
> +
> +	pm_runtime_get_sync(qspi->dev);
> +
> +	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;
> +	}
> +
> +	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;
> +	}
> +
> +	/* 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);
> +
> +	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);

not going to check return value ?

> +	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);

what about on these two ?

> +	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);

you should enable the interrupt as the last step. Also, why aren't you
using frame interrupt ?

> +		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);

ditto

> +		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);
> +		dev_dbg(qspi->dev, "rx done, read %02x\n", *(rxbuf-1));
> +	}
> +
> +	return 0;
> +}
> +
> +static int qspi_transfer_msg(struct dra7xxx_qspi *qspi, struct spi_transfer *t)
> +{
> +	if (t->tx_buf)
> +		qspi_write_msg(qspi, t);
> +	if (t->rx_buf)
> +		qspi_read_msg(qspi, t);
> +
> +	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,

why this multiplication ? Frame is not counted in bits but in number of
words. Which means that m->framelength / spi->bits_per_word should be
enough.

Also, this actually brings up a mistake I made, if I read the TRM
correclty this time, frame length is nothing but the t->len which
renders patch 1 in this series unnecessary, my mistake.

> +				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);

right, right, so far so good...

> +	list_for_each_entry(t, &m->transfers, transfer_list) {
> +		qspi->cmd |= QSPI_WLEN(t->bits_per_word);

sure about this ? according to TRM a write of 0 means 1 bit, 1, means 2
bits, 2 means 3 bits, etc... So this should be t->bits_per_word - 1.

> +		qspi->cmd |= QSPI_WC_CMD_INT_EN;

... but why are you still interrupting on every word ????

as I said before, we want to interrupt on every frame. one spi_transfer
is one frame, if that frame has a length of 1MiB, I want to be
interrupted after 1MiB.

> +		qspi_transfer_msg(qspi, t);
> +		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);
> +
> +	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))

this is wrong, everytime you want to handle another IRQ bit, you will
have to update this line.

	if (stat & mask)

sounds like it's enough

-- 
balbi

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