On 11/12/2012 10:00 PM, Laxman Dewangan wrote:
> Nvidia's Tegra20 have the SPI (SFLASH) controller to
> interface with spi flash device which is used for system
> boot. Add the spi driver for this controller.
> diff --git a/drivers/spi/spi-tegra20-sflash.c
> b/drivers/spi/spi-tegra20-sflash.c
> +static void tegra_sflash_clear_status(struct tegra_sflash_data *tsd)
> +{
> + unsigned long val;
> + unsigned long val_write = 0;
> +
> + val = tegra_sflash_readl(tsd, SPI_STATUS);
Why the read of the unused value. Is this to flush earlier bus
transactions, or just left over? If for bus flushing, a comment would be
useful.
> + /* Write 1 to clear status register */
> + val_write = SPI_RDY | SPI_FIFO_ERROR;
> + tegra_sflash_writel(tsd, val_write, SPI_STATUS);
> +}
> +static irqreturn_t handle_cpu_based_xfer(struct tegra_sflash_data *tsd)
> +{
> + struct spi_transfer *t = tsd->curr_xfer;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&tsd->lock, flags);
> + if (tsd->tx_status || tsd->rx_status ||
Nit: double-space after first || above.
> +static struct tegra_spi_platform_data *tegra_sflash_parse_dt(
> + struct platform_device *pdev)
> + prop = of_get_property(np, "spi-max-frequency", NULL);
> + if (prop)
> + pdata->spi_max_frequency = be32_to_cpup(prop);
Perhaps use of_property_read_u32()?
> +static int __devinit tegra_sflash_probe(struct platform_device *pdev)
> + tsd->clk = devm_clk_get(&pdev->dev, "spi");
> + if (IS_ERR(tsd->clk)) {
> + dev_err(&pdev->dev, "can not get clock\n");
> + ret = PTR_ERR(tsd->clk);
> + goto exit_free_irq;
> + }
> +
> +
> + tsd->spi_max_frequency = pdata->spi_max_frequency;
Nit: Double blank-line there.
> +static int tegra_sflash_resume(struct device *dev)
> +{
> + struct spi_master *master = dev_get_drvdata(dev);
> + struct tegra_sflash_data *tsd = spi_master_get_devdata(master);
> + int ret;
> +
> + ret = pm_runtime_get_sync(dev);
> + if (ret < 0) {
> + dev_err(dev, "pm runtime failed, e = %d\n", ret);
> + return ret;
> + }
> + tegra_sflash_writel(tsd, tsd->command_reg, SPI_COMMAND);
> + pm_runtime_put(dev);
Can we avoid this whole function simply by programming SPI_COMMAND at
the start of each transaction? That seems simpler. I assume that
shouldn't e.g. leave any chip-selects in some bad state, or at least if
it does, that shouldn't be a problem, because before the driver probes()
at kernel boot, SPI_COMMAND won't have been programmed either.
Aside from that,
Acked-by: Stephen Warren <swar...@nvidia.com>
Tested-by: Stephen Warren <swar...@nvidia.com>
Thanks.
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