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Date: Fri, 15 Jul 2016 17:45:07 -0700
From: Brian Norris <computersforpeace@...il.com>
To: Cyrille Pitchen <cyrille.pitchen@...el.com>
Cc: linux-mtd@...ts.infradead.org, nicolas.ferre@...el.com,
boris.brezillon@...e-electrons.com, marex@...x.de,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] mtd: atmel-quadspi: add driver for Atmel QSPI
controller
Hi Cyrille,
On Wed, Jul 13, 2016 at 06:32:42PM -0700, Brian Norris wrote:
> On Mon, Jun 13, 2016 at 05:10:26PM +0200, Cyrille Pitchen wrote:
> > This driver add support to the new Atmel QSPI controller embedded into
> > sama5d2x SoCs. It expects a NOR memory to be connected to the QSPI
> > controller.
> >
> > Signed-off-by: Cyrille Pitchen <cyrille.pitchen@...el.com>
> > Acked-by: Nicolas Ferre <nicolas.ferre@...el.com>
> > ---
> > drivers/mtd/spi-nor/Kconfig | 9 +
> > drivers/mtd/spi-nor/Makefile | 1 +
> > drivers/mtd/spi-nor/atmel-quadspi.c | 741 ++++++++++++++++++++++++++++++++++++
> > 3 files changed, 751 insertions(+)
> > create mode 100644 drivers/mtd/spi-nor/atmel-quadspi.c
> >
> > diff --git a/drivers/mtd/spi-nor/Kconfig b/drivers/mtd/spi-nor/Kconfig
> > index d42c98e1f581..c546efd1357b 100644
> > --- a/drivers/mtd/spi-nor/Kconfig
> > +++ b/drivers/mtd/spi-nor/Kconfig
> > @@ -38,6 +38,15 @@ config SPI_FSL_QUADSPI
> > This controller does not support generic SPI. It only supports
> > SPI NOR.
> >
> > +config SPI_ATMEL_QUADSPI
> > + tristate "Atmel Quad SPI Controller"
> > + depends on ARCH_AT91 || (ARM && COMPILE_TEST)
> > + depends on OF && HAS_IOMEM
> > + help
> > + This enables support for the Quad SPI controller in master mode.
> > + This driver does not support generic SPI. The implementation only
> > + supports SPI NOR.
> > +
> > config SPI_NXP_SPIFI
> > tristate "NXP SPI Flash Interface (SPIFI)"
> > depends on OF && (ARCH_LPC18XX || COMPILE_TEST)
> > diff --git a/drivers/mtd/spi-nor/Makefile b/drivers/mtd/spi-nor/Makefile
> > index 0bf3a7f81675..1525913698ad 100644
> > --- a/drivers/mtd/spi-nor/Makefile
> > +++ b/drivers/mtd/spi-nor/Makefile
> > @@ -2,3 +2,4 @@ obj-$(CONFIG_MTD_SPI_NOR) += spi-nor.o
> > obj-$(CONFIG_SPI_FSL_QUADSPI) += fsl-quadspi.o
> > obj-$(CONFIG_MTD_MT81xx_NOR) += mtk-quadspi.o
> > obj-$(CONFIG_SPI_NXP_SPIFI) += nxp-spifi.o
> > +obj-$(CONFIG_SPI_ATMEL_QUADSPI) += atmel-quadspi.o
> > diff --git a/drivers/mtd/spi-nor/atmel-quadspi.c b/drivers/mtd/spi-nor/atmel-quadspi.c
> > new file mode 100644
> > index 000000000000..06d1bf276dd0
> > --- /dev/null
> > +++ b/drivers/mtd/spi-nor/atmel-quadspi.c
> > @@ -0,0 +1,741 @@
>
> [...]
>
> > +struct atmel_qspi_command {
> > + union {
> > + struct {
> > + u32 instruction:1;
> > + u32 address:3;
> > + u32 mode:1;
> > + u32 dummy:1;
> > + u32 data:1;
> > + u32 reserved:25;
> > + } bits;
>
> Are you sure this bitfield is going to do what you want, all the time?
> What about on big-endian architectures? And are you guaranteed it'll
> pack properly, with no padding? IIRC, the answer to the first 2 is "no",
> and I have no idea about the 3rd. Honestly, I've been scared away from
> using bitfields on anything where the ordering mattered, and I thought
> that's because I was hurt by the lack of guarantee once. But I easily
> could be misguided.
>
> > + u32 word;
> > + } enable;
> > + u8 instruction;
> > + u8 mode;
> > + u8 num_mode_cycles;
> > + u8 num_dummy_cycles;
> > + u32 address;
> > +
> > + size_t buf_len;
> > + const void *tx_buf;
> > + void *rx_buf;
> > +};
> > +
>
> [...]
>
> > +static int atmel_qspi_probe(struct platform_device *pdev)
> > +{
> > + struct device_node *child, *np = pdev->dev.of_node;
> > + char modalias[SPI_NAME_SIZE];
> > + const char *name = NULL;
> > + struct atmel_qspi *aq;
> > + struct resource *res;
> > + struct spi_nor *nor;
> > + struct mtd_info *mtd;
> > + int irq, err = 0;
> > +
> > + if (of_get_child_count(np) != 1)
> > + return -ENODEV;
> > + child = of_get_next_child(np, NULL);
> > +
> > + aq = devm_kzalloc(&pdev->dev, sizeof(*aq), GFP_KERNEL);
> > + if (!aq) {
> > + err = -ENOMEM;
> > + goto exit;
> > + }
> > +
> > + platform_set_drvdata(pdev, aq);
> > + init_completion(&aq->cmd_completion);
> > + aq->pdev = pdev;
> > +
> > + /* Map the registers */
> > + res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "qspi_base");
> > + aq->regs = devm_ioremap_resource(&pdev->dev, res);
> > + if (IS_ERR(aq->regs)) {
> > + dev_err(&pdev->dev, "missing registers\n");
> > + err = PTR_ERR(aq->regs);
> > + goto exit;
> > + }
> > +
> > + /* Map the AHB memory */
> > + res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "qspi_mmap");
> > + aq->mem = devm_ioremap_resource(&pdev->dev, res);
> > + if (IS_ERR(aq->mem)) {
> > + dev_err(&pdev->dev, "missing AHB memory\n");
> > + err = PTR_ERR(aq->mem);
> > + goto exit;
> > + }
> > +
> > + /* Get the peripheral clock */
> > + aq->clk = devm_clk_get(&pdev->dev, NULL);
> > + if (IS_ERR(aq->clk)) {
> > + dev_err(&pdev->dev, "missing peripheral clock\n");
> > + err = PTR_ERR(aq->clk);
> > + goto exit;
> > + }
> > +
> > + /* Enable the peripheral clock */
> > + err = clk_prepare_enable(aq->clk);
> > + if (err) {
> > + dev_err(&pdev->dev, "failed to enable the peripheral clock\n");
> > + goto exit;
> > + }
> > +
> > + /* Request the IRQ */
> > + irq = platform_get_irq(pdev, 0);
> > + if (irq < 0) {
> > + dev_err(&pdev->dev, "missing IRQ\n");
> > + err = irq;
> > + goto disable_clk;
> > + }
> > + err = devm_request_irq(&pdev->dev, irq, atmel_qspi_interrupt,
> > + 0, dev_name(&pdev->dev), aq);
> > + if (err)
> > + goto disable_clk;
> > +
> > + /* Setup the spi-nor */
> > + nor = &aq->nor;
> > + mtd = &nor->mtd;
> > +
> > + nor->dev = &pdev->dev;
> > + spi_nor_set_flash_node(nor, child);
> > + nor->priv = aq;
> > + mtd->priv = nor;
> > +
> > + nor->read_reg = atmel_qspi_read_reg;
> > + nor->write_reg = atmel_qspi_write_reg;
> > + nor->read = atmel_qspi_read;
> > + nor->write = atmel_qspi_write;
> > + nor->erase = atmel_qspi_erase;
> > +
> > + err = of_modalias_node(child, modalias, sizeof(modalias));
> > + if (err < 0)
> > + goto disable_clk;
> > +
> > + if (strcmp(modalias, "spi-nor"))
> > + name = modalias;
>
> What is this modalias handling for? Are you trying to support passing in
> a flash-specific string, like m25p80 does? And you're enforcing that to
> be only the first entry in the 'compatible' list? Seems fragile; m25p80
> is a special case (and it's already fragile) that I'd rather not
> imitate.
>
> I understand that we discussed extending the use of compatible for
> spi-nor drivers, but I still don't think that issue is resolved. And if
> we are going to extend the use of compatible, then I think we should
> fixup all the spi-nor drivers in the same way.
>
> > +
> > + err = of_property_read_u32(child, "spi-max-frequency", &aq->clk_rate);
> > + if (err < 0)
> > + goto disable_clk;
> > +
> > + err = atmel_qspi_init(aq);
> > + if (err)
> > + goto disable_clk;
> > +
> > + err = spi_nor_scan(nor, name, SPI_NOR_QUAD);
> > + if (err)
> > + goto disable_clk;
> > +
> > + err = mtd_device_register(mtd, NULL, 0);
> > + if (err)
> > + goto disable_clk;
> > +
> > + of_node_put(child);
> > +
> > + return 0;
> > +
> > +disable_clk:
> > + clk_disable_unprepare(aq->clk);
> > +exit:
> > + of_node_put(child);
> > +
> > + return err;
> > +}
> > +
> > +static int atmel_qspi_remove(struct platform_device *pdev)
> > +{
> > + struct atmel_qspi *aq = platform_get_drvdata(pdev);
> > +
> > + mtd_device_unregister(&aq->nor.mtd);
> > + qspi_writel(aq, QSPI_CR, QSPI_CR_QSPIDIS);
> > + clk_disable_unprepare(aq->clk);
> > + return 0;
> > +}
> > +
> > +
> > +static const struct of_device_id atmel_qspi_dt_ids[] = {
> > + { .compatible = "atmel,sama5d2-qspi" },
> > + { /* sentinel */ }
> > +};
> > +
> > +MODULE_DEVICE_TABLE(of, atmel_qspi_dt_ids);
> > +
> > +static struct platform_driver atmel_qspi_driver = {
> > + .driver = {
> > + .name = "atmel_qspi",
> > + .of_match_table = atmel_qspi_dt_ids,
> > + },
> > + .probe = atmel_qspi_probe,
> > + .remove = atmel_qspi_remove,
> > +};
> > +module_platform_driver(atmel_qspi_driver);
> > +
> > +MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@...el.com>");
> > +MODULE_DESCRIPTION("Atmel QSPI Controller driver");
> > +MODULE_LICENSE("GPL v2");
>
> I'm likely to apply this driver, with the following diff (the bitfield
> issue (if there is one) is less of a maintenance issue), barring any
> major objections.
>
> diff --git a/drivers/mtd/spi-nor/atmel-quadspi.c b/drivers/mtd/spi-nor/atmel-quadspi.c
> index 06d1bf276dd0..47937d9beec6 100644
> --- a/drivers/mtd/spi-nor/atmel-quadspi.c
> +++ b/drivers/mtd/spi-nor/atmel-quadspi.c
> @@ -591,8 +591,6 @@ static irqreturn_t atmel_qspi_interrupt(int irq, void *dev_id)
> static int atmel_qspi_probe(struct platform_device *pdev)
> {
> struct device_node *child, *np = pdev->dev.of_node;
> - char modalias[SPI_NAME_SIZE];
> - const char *name = NULL;
> struct atmel_qspi *aq;
> struct resource *res;
> struct spi_nor *nor;
> @@ -673,13 +671,6 @@ static int atmel_qspi_probe(struct platform_device *pdev)
> nor->write = atmel_qspi_write;
> nor->erase = atmel_qspi_erase;
>
> - err = of_modalias_node(child, modalias, sizeof(modalias));
> - if (err < 0)
> - goto disable_clk;
> -
> - if (strcmp(modalias, "spi-nor"))
> - name = modalias;
> -
> err = of_property_read_u32(child, "spi-max-frequency", &aq->clk_rate);
> if (err < 0)
> goto disable_clk;
> @@ -688,7 +679,7 @@ static int atmel_qspi_probe(struct platform_device *pdev)
> if (err)
> goto disable_clk;
>
> - err = spi_nor_scan(nor, name, SPI_NOR_QUAD);
> + err = spi_nor_scan(nor, NULL, SPI_NOR_QUAD);
> if (err)
> goto disable_clk;
>
Applied to l2-mtd.git with that fixup.
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