Re: [PATCH v2 2/4] leds: simatic-ipc-leds: add new driver for Siemens Industial PCs

Andy Shevchenko
2021-03-15T10:49:16Z

On Mon, Mar 15, 2021 at 11:57 AM Henning Schild
<henning.schild@siemens.com> wrote:
>
> This driver adds initial support for several devices from Siemens. It is
> based on a platform driver introduced in an earlier commit.

...

> +struct simatic_ipc_led {
> + unsigned int value; /* mask for io and offset for mem */

> + char name[32];

Hmm... Dunno if LED framework defines its own constraints for the
length of the name.

> + struct led_classdev cdev;
> +};
> +
> +static struct simatic_ipc_led simatic_ipc_leds_io[] = {
> + {1 << 15, "simatic-ipc:green:" LED_FUNCTION_STATUS "-1" },
> + {1 << 7, "simatic-ipc:yellow:" LED_FUNCTION_STATUS "-1" },
> + {1 << 14, "simatic-ipc:red:" LED_FUNCTION_STATUS "-2" },
> + {1 << 6, "simatic-ipc:yellow:" LED_FUNCTION_STATUS "-2" },
> + {1 << 13, "simatic-ipc:red:" LED_FUNCTION_STATUS "-3" },
> + {1 << 5, "simatic-ipc:yellow:" LED_FUNCTION_STATUS "-3" },

Can you use BIT() macro here? And can it be sorted by the bit order?

> + {0, ""},

{ } is enough (no comma for terminator lines in general, and no need
to show structure member assignments separately in particular).

> +};
> +
> +/* the actual start will be discovered with pci, 0 is a placeholder */

PCI

> +struct resource simatic_ipc_led_mem_res =
> + DEFINE_RES_MEM_NAMED(0, SZ_4K, KBUILD_MODNAME);

One line?

...

> +static struct simatic_ipc_led simatic_ipc_leds_mem[] = {
> + {0x500 + 0x1A0, "simatic-ipc:red:" LED_FUNCTION_STATUS "-1"},
> + {0x500 + 0x1A8, "simatic-ipc:green:" LED_FUNCTION_STATUS "-1"},
> + {0x500 + 0x1C8, "simatic-ipc:red:" LED_FUNCTION_STATUS "-2"},
> + {0x500 + 0x1D0, "simatic-ipc:green:" LED_FUNCTION_STATUS "-2"},
> + {0x500 + 0x1E0, "simatic-ipc:red:" LED_FUNCTION_STATUS "-3"},
> + {0x500 + 0x198, "simatic-ipc:green:" LED_FUNCTION_STATUS "-3"},
> + {0, ""},

As per above.

> +};

...

> + struct simatic_ipc_led *led =
> + container_of(led_cd, struct simatic_ipc_led, cdev);

One line?

...

> + struct simatic_ipc_led *led =
> + container_of(led_cd, struct simatic_ipc_led, cdev);

One line?

...

> + struct simatic_ipc_led *led =
> + container_of(led_cd, struct simatic_ipc_led, cdev);

Ditto.

Btw, usually for such cases we create an inline helper
... to_simatic_ipc_led(...)
{
return container_of(...);
}

...

> +static int simatic_ipc_leds_probe(struct platform_device *pdev)
> +{
> + struct simatic_ipc_platform *plat;

const?

> + struct device *dev = &pdev->dev;
> + struct simatic_ipc_led *ipcled;
> + struct led_classdev *cdev;
> + struct resource *res;
> + int err, type;
> + u32 *p;

> + plat = pdev->dev.platform_data;

Can be done directly in the definition block.

> + switch (plat->devmode) {
> + case SIMATIC_IPC_DEVICE_227D:
> + case SIMATIC_IPC_DEVICE_427E:
> + res = &simatic_ipc_led_io_res;
> + ipcled = simatic_ipc_leds_io;
> + /* the 227D is high on while 427E is low on, invert the struct
> + * we have
> + */
> + if (plat->devmode == SIMATIC_IPC_DEVICE_227D) {

> + while (ipcled->value) {
> + ipcled->value = swab16(ipcled->value);
> + ipcled++;
> + }

This seems fishy. If you have a BE CPU it won't work the same way.
Better:
a) to use cpu_to_le16 / be16
b) create this as a helper that we may move to the generic header of byteorder.

But looking at the use of it, perhaps you rather need to redefine IO
accessors, i.e. ioread16()/iowrite16() vs. ioread16be()/iowrite16be().

> + ipcled = simatic_ipc_leds_io;
> + }
> + type = IORESOURCE_IO;
> + if (!devm_request_region(dev, res->start,
> + resource_size(res),
> + KBUILD_MODNAME)) {
> + dev_err(dev,
> + "Unable to register IO resource at %pR\n",
> + res);
> + return -EBUSY;
> + }
> + break;
> + case SIMATIC_IPC_DEVICE_127E:
> + res = &simatic_ipc_led_mem_res;
> + ipcled = simatic_ipc_leds_mem;
> + type = IORESOURCE_MEM;
> +
> + /* get GPIO base from PCI */
> + res->start = simatic_ipc_get_membase0(PCI_DEVFN(13, 0));
> + if (res->start == 0)
> + return -ENODEV;
> +
> + /* do the final address calculation */
> + res->start = res->start + (0xC5 << 16);

Magic. As I told you this is an actual offseet in the P2SB's bar for
GPIO registers.
I have a question, why we can't provide a GPIO driver which is already
in the kernel and, with use of the patch series I sent, to convert
this all magic to GPIO LEDs as it's done for all normal cases?

> + res->end += res->start;
> +
> + simatic_ipc_led_memory = devm_ioremap_resource(dev, res);
> + if (IS_ERR(simatic_ipc_led_memory))
> + return PTR_ERR(simatic_ipc_led_memory);
> +
> + /* initialize power/watchdog LED */
> + p = simatic_ipc_led_memory + 0x500 + 0x1D8; /* PM_WDT_OUT */
> + *p = (*p & ~1);
> + p = simatic_ipc_led_memory + 0x500 + 0x1C0; /* PM_BIOS_BOOT_N */
> + *p = (*p | 1);
> +
> + break;
> + default:
> + return -ENODEV;
> + }

> +}

--
With Best Regards,
Andy Shevchenko