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SubjectRe: [PATCH v3 5/6] spi: at91-usart: add driver for at91-usart as spi
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On Sun, 2018-05-13 at 16:33 +0300, Andy Shevchenko wrote:
> 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(&pde
> > v->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.

This driver can not work as pure platform driver, but I the way I used
to probe it from MFD(by compatbile string).
Do you know another way?

>
> > + },
> > + .probe = at91_usart_spi_probe,
> > + .remove = at91_usart_spi_remove, };
>
> Two lines at one. Split.
>

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