Re: [PATCH v2 2/4] leds: simatic-ipc-leds: add new driver for Siemens Industial PCs
From: Enrico Weigelt, metux IT consult
Date: Thu Mar 18 2021 - 06:26:43 EST
On 15.03.21 10:57, Henning Schild wrote:
Hi,
diff --git a/drivers/leds/simple/simatic-ipc-leds.c b/drivers/leds/simple/simatic-ipc-leds.c
new file mode 100644
index 000000000000..0f7e6320e10d
--- /dev/null
+++ b/drivers/leds/simple/simatic-ipc-leds.c
@@ -0,0 +1,210 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Siemens SIMATIC IPC driver for LEDs
+ *
+ * Copyright (c) Siemens AG, 2018-2021
+ *
+ * Authors:
+ * Henning Schild <henning.schild@xxxxxxxxxxx>
+ * Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
+ * Gerd Haeussler <gerd.haeussler.ext@xxxxxxxxxxx>
+ */
+
+#include <linux/ioport.h>
+#include <linux/kernel.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/platform_data/x86/simatic-ipc-base.h>
+#include <linux/platform_device.h>
+#include <linux/sizes.h>
+#include <linux/spinlock.h>
+
+#define SIMATIC_IPC_LED_PORT_BASE 0x404E
+
+struct simatic_ipc_led {
+ unsigned int value; /* mask for io and offset for mem */
+ char name[32];
+ 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" },
+ {0, ""},
+};
Wouldn't it be better to name them like they're labeled on the device,
as shown on page #19 of the manual, or perhaps a little bit more
generic nameing (eg. power, status, error, maint) ?
+/* the actual start will be discovered with pci, 0 is a placeholder */
+struct resource simatic_ipc_led_mem_res =
+ DEFINE_RES_MEM_NAMED(0, SZ_4K, KBUILD_MODNAME);
> +
> +static void *simatic_ipc_led_memory;
> +
hmm, could there *ever* be multiple instances of the driver ?
Wouldn't it be better to put this in the device priv data instead ?
+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, ""},
+};
+
+static struct resource simatic_ipc_led_io_res =
+ DEFINE_RES_IO_NAMED(SIMATIC_IPC_LED_PORT_BASE, SZ_1, KBUILD_MODNAME);
+
+static DEFINE_SPINLOCK(reg_lock);
Does this protect global data structures ? If not, I'd rather put it
into the device priv data instead.
BTW: doesn't have struct led_classdev already have a lock that
can be used ? Can multiple calls to led ops (within the same device)
at the same time happen at all, or does led core already serialize
that ?
+static void simatic_ipc_led_set_io(struct led_classdev *led_cd,
+ enum led_brightness brightness)
+{
+ struct simatic_ipc_led *led =
+ container_of(led_cd, struct simatic_ipc_led, cdev);
+ unsigned long flags;
+ unsigned int val;
+
+ spin_lock_irqsave(®_lock, flags);
+
+ val = inw(SIMATIC_IPC_LED_PORT_BASE);
+ if (brightness == LED_OFF)
+ outw(val | led->value, SIMATIC_IPC_LED_PORT_BASE);
+ else
+ outw(val & ~led->value, SIMATIC_IPC_LED_PORT_BASE);
Don't we already have an helper for setting or clearing bits in IO
registers (that already does the read + set/clear + write at once) ?
Does that really need to be protected by lock ?
(can happen multiple calls to that func from different threads happen
at all ?)
Is the port really *always* the same, so it really can be a const ?
<snip>
+static int simatic_ipc_leds_probe(struct platform_device *pdev)
+{
+ struct simatic_ipc_platform *plat;
+ 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;
Maybe put this into swnode ?
IIRC, the consensus is not to introduce new platform data structs
anymore, instead legacy pdata to swnode some day.
+ 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);
Uff, better use explicit endian conversion macros (eg. be*_to_cpu()) for
that.
Also, I wouldn't change those global structs, instead put those data
into device priv data and make the global stuff const. You could also
use the same field for both port-io and mmap'ed variants. And adding
regmap to the equation, could use the same led ops for both. (IMHO,
the little bit of overhead by regmap shouldn't matter here)
+ ipcled++;
+ }
+ 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;
Where does that device actually sit on ? Some generic card ? Some ASIC
or FPGA ?
It seems this driver is instantiated by another one, which already knows
what device we're actually dealing with (as it sets plat->devmode).
Why not letting that parent device also tell the io resource to this
driver ?
+ while (ipcled->value) {
+ cdev = &ipcled->cdev;
+ cdev->brightness_set = simatic_ipc_led_set_io;
+ cdev->brightness_get = simatic_ipc_led_get_io;
+ if (type == IORESOURCE_MEM) {
+ cdev->brightness_set = simatic_ipc_led_set_mem;
+ cdev->brightness_get = simatic_ipc_led_get_mem;
+ }
Why not if/else ?
+ cdev->max_brightness = LED_ON;
+ cdev->name = ipcled->name;
+
+ err = devm_led_classdev_register(dev, cdev);
+ if (err < 0)
+ return err;
+ ipcled++;
+ }
+
+ return 0;
+}
+
+static struct platform_driver led_driver = {
Why not calling it simatic_ipc_led_driver ?
+ .probe = simatic_ipc_leds_probe,
+ .driver = {
+ .name = KBUILD_MODNAME,
+ },
+};
+
+module_platform_driver(led_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" KBUILD_MODNAME);
+MODULE_AUTHOR("Henning Schild <henning.schild@xxxxxxxxxxx>");
--mtx
--
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Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
info@xxxxxxxxx -- +49-151-27565287