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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Sun, 13 May 2018 16:33:40 +0300
Message-ID: <CAHp75Ve3Ugnjjm8EZkPQTZSvH1qad1e5SqjOn8zz5syHSQea_g@mail.gmail.com>
Subject: Re: [PATCH v3 5/6] spi: at91-usart: add driver for at91-usart as spi
To:     Radu Pirea <radu.pirea@microchip.com>
Cc:     devicetree <devicetree@vger.kernel.org>,
        "open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
        linux-spi <linux-spi@vger.kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Rob Herring <robh+dt@kernel.org>,
        Lee Jones <lee.jones@linaro.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jslaby@suse.com>,
        Richard Genoud <richard.genoud@gmail.com>,
        alexandre.belloni@bootlin.com,
        Nicolas Ferre <nicolas.ferre@microchip.com>,
        Mark Brown <broonie@kernel.org>
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On Fri, May 11, 2018 at 1:38 PM, Radu Pirea <radu.pirea@microchip.com> wrote:
> This is the driver for at91-usart in spi mode. The USART IP can be configured
> to work in many modes and one of them is SPI.

> +#include <linux/gpio.h>
> +#include <linux/gpio/consumer.h>

Here is something wrong. You need to use latter one in new code.

> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/of_gpio.h>

Hmm... Do you need all of them?

> +static inline void at91_usart_spi_cs_activate(struct spi_device *spi)
> +{
...
> +       gpiod_set_value(ausd->npcs_pin, active);
> +       aus->cs_active = true;
> +}
> +
> +static inline void at91_usart_spi_cs_deactivate(struct spi_device *spi)
> +{
...
> +       gpiod_set_value(ausd->npcs_pin, !active);
> +       aus->cs_active = false;
> +}
...
> +       if (!ausd) {
> +               if (gpio_is_valid(spi->cs_gpio)) {
> +                       npcs_pin = gpio_to_desc(spi->cs_gpio);
...
> +               }
...
> +               gpiod_direction_output(npcs_pin, !(spi->mode & SPI_CS_HIGH));
> +
> +               ausd->npcs_pin = npcs_pin;
...
> +       }

I will refer to above as (1) later on.

> +       dev_dbg(&spi->dev, "new message %p submitted for %s\n",
> +               msg, dev_name(&spi->dev));

%p does make a very little sense.

> +       list_for_each_entry(xfer, &msg->transfers, transfer_list) {
> +               ret = at91_usart_spi_one_transfer(controller, msg, xfer);
> +               if (ret)
> +                       goto msg_done;
> +       }

Cant SPI core do this for your?

> +static void at91_usart_spi_cleanup(struct spi_device *spi)
> +{
> +       struct at91_usart_spi_device *ausd = spi->controller_state;
> +

> +       if (!ausd)
> +               return;

Is it even possible?

Anyway the code below will work fine even if it's the case.

> +
> +       spi->controller_state = NULL;
> +       kfree(ausd);
> +}

> +static int at91_usart_spi_gpio_cs(struct platform_device *pdev)
> +{
> +       struct spi_controller *controller = platform_get_drvdata(pdev);
> +       struct device_node *np = controller->dev.parent->of_node;
> +       struct gpio_desc *cs_gpio;
> +       int nb;
> +       int i;
> +
> +       if (!np)
> +               return 0;
> +
> +       nb = of_gpio_named_count(np, "cs-gpios");
> +       for (i = 0; i < nb; i++) {
> +               cs_gpio = devm_gpiod_get_from_of_node(&pdev->dev,
> +                                                     pdev->dev.parent->of_node,
> +                                                     "cs-gpios",
> +                                                     i, GPIOD_OUT_HIGH,
> +                                                     dev_name(&pdev->dev));
> +               if (IS_ERR(cs_gpio))
> +                       return PTR_ERR(cs_gpio);
> +       }
> +
> +       controller->num_chipselect = nb;
> +
> +       return 0;
> +}

The question is, why you didn't utilize what SPI core provides you?

> +       spi_writel(aus, MR, US_MR_SPI_MASTER | US_MR_CHRL | US_MR_CLKO |
> +                       US_MR_WRDBT);
> +       spi_writel(aus, CR, US_CR_RXDIS | US_CR_TXDIS | US_CR_RSTRX |
> +                       US_CR_RSTTX);

I didn't check over, but it seems like you might have duplication in
these bitwise ORs. Consider to unify them into another (shorter)
definitions and reuse all over the code.

> +       regs = platform_get_resource(to_platform_device(pdev->dev.parent),
> +                                    IORESOURCE_MEM, 0);
> +       if (!regs)
> +               return -ENXIO;

Strange error code for getting MMIO resource. ENOMEM sounds better.

> +       dev_info(&pdev->dev,
> +                "Atmel USART SPI Controller version 0x%x at 0x%08lx (irq %d)\n",
> +                spi_readl(aus, VERSION),
> +                (unsigned long)regs->start, irq);

If you do explicit casting when printing something you are doing wrong.
Please use %pR or %pr in this case.

> +static struct platform_driver at91_usart_spi_driver = {
> +       .driver = {
> +               .name = "at91_usart_spi",

> +               .of_match_table = of_match_ptr(at91_usart_spi_dt_ids),

Can it work as pure platform driver? If no, of_match_ptr() is redundant.

> +       },
> +       .probe = at91_usart_spi_probe,
> +       .remove = at91_usart_spi_remove, };

Two lines at one. Split.

-- 
With Best Regards,
Andy Shevchenko