On Sun, Mar 7, 2021 at 11:21 AM Andy Shevchenko
[off-list ref] wrote:

On Thu, Mar 4, 2021 at 4:40 PM Brad Larson [off-list ref] wrote:

quoted

This GPIO driver is for the Pensando Elba SoC which
provides control of four chip selects on two SPI busses.

quoted

+config GPIO_ELBA_SPICS
+       bool "Pensando Elba SPI chip-select"

Can't it be a module? Why?

All Elba SoC based platforms require this driver to be built-in to boot and
removing the module would result in a variety of exceptions/errors.

quoted

+       depends on ARCH_PENSANDO_ELBA_SOC
+       help
+         Say yes here to support the Pensndo Elba SoC SPI chip-select driver

Please give more explanation what it is and why users might need it,
and also tell users how the module will be named (if there is no
strong argument why it can't be a  module).

Fixed the typo.

quoted

+#include <linux/of.h>

It's not used here, but you missed mod_devicetable.h.

Removed <linux/of.h>.  There is no dependency on mod_devicetable.h.

...

quoted

+/*
+ * pin:             3            2        |       1            0
+ * bit:         7------6------5------4----|---3------2------1------0
+ *     cs1  cs1_ovr  cs0  cs0_ovr |  cs1  cs1_ovr  cs0  cs0_ovr
+ *                ssi1            |             ssi0
+ */
+#define SPICS_PIN_SHIFT(pin)   (2 * (pin))
+#define SPICS_MASK(pin)                (0x3 << SPICS_PIN_SHIFT(pin))

quoted

+#define SPICS_SET(pin, val)    ((((val) << 1) | 0x1) << SPICS_PIN_SHIFT(pin))

Isn't it easier to define as ((value) << (2 * (pin) + 1) | BIT(2 * (pin)))

...

quoted

+struct elba_spics_priv {
+       void __iomem *base;
+       spinlock_t lock;

quoted

+       struct gpio_chip chip;

If you put it as a first member a container_of() becomes a no-op. OTOH
dunno if there is any such container_of() use in the code.

There is no use of container_of()

quoted

+static int elba_spics_get_value(struct gpio_chip *chip, unsigned int pin)
+{
+       return -ENXIO;

Hmm... Is it really acceptable error code here?

quoted

+static int elba_spics_direction_input(struct gpio_chip *chip, unsigned int pin)
+{
+       return -ENXIO;

Ditto.

Changed both to -ENOTSUPP.

quoted

+       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+       p->base = devm_ioremap_resource(&pdev->dev, res);

p->base = devm_platform_ioremap_resource(pdev, 0);

Implementation follows devm_ioremap_resource() example in lib/devres.c.

quoted

+       if (IS_ERR(p->base)) {

quoted

+               dev_err(&pdev->dev, "failed to remap I/O memory\n");

Duplicate noisy message.

quoted

+               return PTR_ERR(p->base);
+       }

quoted

+       ret = devm_gpiochip_add_data(&pdev->dev, &p->chip, p);
+       if (ret) {
+               dev_err(&pdev->dev, "unable to add gpio chip\n");

quoted

+               return ret;
+       }
+
+       dev_info(&pdev->dev, "elba spics registered\n");
+       return 0;

if (ret)
  dev_err(...);
return ret;

Cleaned this up in patchset v2.

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