On Fri, May 25, 2018 at 8:19 PM, Radu Pirea [off-list ref] 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.

The driver was tested on sama5d3-xplained and sama5d4-xplained boards with
enc28j60 ethernet controller as slave.

+#include <linux/of_gpio.h>

What is the use of it?

+#define US_INIT                        (US_MR_SPI_MASTER | US_MR_CHRL | US_MR_CLKO | \
+                               US_MR_WRDBT)

Don't split lines like this, it's hard to read.

#define FOO \
 (BAR1 | BAR2)

I think I already told this to someone recently, maybe to you.

+/* Register access macros */
+#define spi_readl(port, reg) \
+       readl_relaxed((port)->regs + US_##reg)
+#define spi_writel(port, reg, value) \
+       writel_relaxed((value), (port)->regs + US_##reg)
+
+#define spi_readb(port, reg) \
+       readb_relaxed((port)->regs + US_##reg)
+#define spi_writeb(port, reg, value) \
+       writeb_relaxed((value), (port)->regs + US_##reg)

Names are too generic. You better to use the same prefix as for the
rest, i.e. at91_spi_

+       /*used in interrupt to protect data reading*/

Comment style.

You need to read some existing code, perhaps, to see how it's done.

+static inline void at91_usart_spi_tx(struct at91_usart_spi *aus)
+{
+       unsigned int len = aus->current_transfer->len;
+       unsigned int remaining = aus->current_tx_remaining_bytes;
+       const u8  *tx_buf = aus->current_transfer->tx_buf;
+

+       if (remaining)
+               if (at91_usart_spi_tx_ready(aus)) {

if (x) {
 if (y) {
...
 }
}

is equivalent to if (x && y) {}.

Though, considering your intention here, I would rather go with better
pattern, i.e.

if (!remaining)
 return;

+                       spi_writeb(aus, THR, tx_buf[len - remaining]);
+                       aus->current_tx_remaining_bytes--;
+               }
+}
+
+static inline void at91_usart_spi_rx(struct at91_usart_spi *aus)
+{

+       if (remaining) {
+               rx_buf[len - remaining] = spi_readb(aus, RHR);
+               aus->current_rx_remaining_bytes--;
+       }

Ditto.

+}

+static int at91_usart_gpio_setup(struct platform_device *pdev)
+{

+       struct device_node      *np = pdev->dev.parent->of_node;

Your driver is not OF specific as far as I can see. Drop all these
device_node stuff and change API calls respectively.

+       int                     i;

+       int                     ret = 0;
+       int                     nb = 0;

What happened to indentation?

Redundnant assignment for both.

+       if (!np)
+               return -EINVAL;
+
+       nb = of_gpio_named_count(np, "cs-gpios");
+       for (i = 0; i < nb; i++) {
+               int cs_gpio = of_get_named_gpio(np, "cs-gpios", i);
+
+               if (cs_gpio < 0)
+                       return cs_gpio;
+
+               if (gpio_is_valid(cs_gpio)) {
+                       ret = devm_gpio_request_one(&pdev->dev, cs_gpio,
+                                                   GPIOF_DIR_OUT,
+                                                   dev_name(&pdev->dev));
+                       if (ret)
+                               return ret;
+               }
+       }
+
+       return 0;
+}
+
+static int at91_usart_spi_probe(struct platform_device *pdev)
+{

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

This looks weird. Supply resource to _this_ device in your MFD code.

+       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);

I think I already told you, don't use explicit casting when print.
If it wasn't you, do you homework then. But above is no go.

+       return 0;

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

+               .of_match_table = of_match_ptr(at91_usart_spi_dt_ids),

Drop of_match_ptr(). It's not needed.

+       },
+       .probe = at91_usart_spi_probe,

+       .remove = at91_usart_spi_remove, };

Already told ya, split lines correctly.

-- 
With Best Regards,
Andy Shevchenko