The Wiegand bus driver spawns devices and matches them with
drivers.
Signed-off-by: Martin Zaťovič <[email protected]>
---
The bus driver currently assumes that any new Wiegand driver will
have a matching entry in the devicetree. It is currently sufficient
as I will only be implementing the GPIO driver. If someone
implements a Wiegand driver that will not use devicetree, he will
also have to edit this bus driver, in order to match properly. Is
that a correct approach?
---
drivers/bus/Kconfig | 6 +
drivers/bus/Makefile | 2 +
drivers/bus/wiegand.c | 339 ++++++++++++++++++++++++++++++++++++++++
include/linux/wiegand.h | 110 +++++++++++++
4 files changed, 457 insertions(+)
create mode 100644 drivers/bus/wiegand.c
create mode 100644 include/linux/wiegand.h
diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index 7bfe998f3514..9675f5a13ffb 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -241,6 +241,12 @@ config VEXPRESS_CONFIG
Platform configuration infrastructure for the ARM Ltd.
Versatile Express.
+config WIEGAND
+ tristate "Wiegand bus"
+ help
+ Wiegand Protocol is a low level 2-wire serial protocol. This
+ enables the support of the bus.
+
config DA8XX_MSTPRI
bool "TI da8xx master peripheral priority driver"
depends on ARCH_DAVINCI_DA8XX
diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
index d90eed189a65..4a9fa6314e54 100644
--- a/drivers/bus/Makefile
+++ b/drivers/bus/Makefile
@@ -36,6 +36,8 @@ obj-$(CONFIG_TI_SYSC) += ti-sysc.o
obj-$(CONFIG_TS_NBUS) += ts-nbus.o
obj-$(CONFIG_UNIPHIER_SYSTEM_BUS) += uniphier-system-bus.o
obj-$(CONFIG_VEXPRESS_CONFIG) += vexpress-config.o
+obj-$(CONFIG_WIEGAND) += wiegand.o
+
obj-$(CONFIG_DA8XX_MSTPRI) += da8xx-mstpri.o
diff --git a/drivers/bus/wiegand.c b/drivers/bus/wiegand.c
new file mode 100644
index 000000000000..c76026d0c3b1
--- /dev/null
+++ b/drivers/bus/wiegand.c
@@ -0,0 +1,339 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/slab.h>
+#include <linux/wiegand.h>
+
+static const struct {
+ const char *name;
+ const char *desc;
+} wiegand_module_table[] = {
+ { NULL, NULL },
+ { "wiegand-gpio", "Wiegand GPIO write-only master" },
+};
+
+int wiegand_gpio_calc_parity8(u8 v)
+{
+ v = (v >> 4) ^ (v & ((1 << 4)-1));
+ v = (v >> 2) ^ (v & ((1 << 2)-1));
+ v = (v >> 1) ^ (v & ((1 << 1)-1));
+ return v;
+}
+EXPORT_SYMBOL_GPL(wiegand_gpio_calc_parity8);
+
+void wiegand_gpio_add_parity_to_data(unsigned char *tmp, u8 *data,
+ enum wiegand_format fmt)
+{
+ switch (fmt) {
+ case WIEGAND_V26:
+ data[0] = (tmp[0] >> 1) | (wiegand_gpio_calc_parity8(
+ tmp[0] ^ (tmp[1] & 0xf0)) << 7);
+ data[1] = (tmp[0] << 7) | (tmp[1] >> 1);
+ data[2] = (tmp[1] << 7) | (tmp[2] >> 1);
+ data[3] = (tmp[2] << 7) | (!wiegand_gpio_calc_parity8(
+ (tmp[1] & 0x0f) ^ tmp[2]) << 6);
+ break;
+ case WIEGAND_V36:
+ tmp[4] &= 0xc0;
+
+ data[0] = (tmp[0] >> 1) | (wiegand_gpio_calc_parity8(
+ tmp[0] ^ tmp[1] ^ (tmp[2] & 0x80)) << 7);
+ data[1] = (tmp[0] << 7) | (tmp[1] >> 1);
+ data[2] = (tmp[1] << 7) | (tmp[2] >> 1);
+ data[3] = (tmp[2] << 7) | (tmp[3] >> 1);
+ data[4] = (tmp[3] << 7) | (tmp[4] >> 1) |
+ (!wiegand_gpio_calc_parity8(
+ (tmp[2] & 0x7f) ^ tmp[3] ^ tmp[4]) << 4);
+ break;
+ case WIEGAND_V37:
+ tmp[4] &= 0xe0;
+
+ data[0] = (tmp[0] >> 1) | (wiegand_gpio_calc_parity8(
+ tmp[0] ^ tmp[1] ^ (tmp[2] & 0xc0)) << 7);
+ data[1] = (tmp[0] << 7) | (tmp[1] >> 1);
+ data[2] = (tmp[1] << 7) | (tmp[2] >> 1);
+ data[3] = (tmp[2] << 7) | (tmp[3] >> 1);
+ data[4] = (tmp[3] << 7) | (tmp[4] >> 1) |
+ (!wiegand_gpio_calc_parity8(
+ (tmp[2] & 0x7f) ^ tmp[3] ^ tmp[4]) << 3);
+ break;
+ default:
+ WARN_ON(fmt != WIEGAND_V37 &&
+ fmt != WIEGAND_V36 &&
+ fmt != WIEGAND_V26);
+ }
+}
+EXPORT_SYMBOL_GPL(wiegand_gpio_add_parity_to_data);
+
+static inline bool wiegand_module_known(unsigned int id)
+{
+ return id >= WIEGAND_MODULE_FIRST && id <= WIEGAND_MODULE_LAST;
+}
+
+static inline const char *wiegand_module_name(unsigned int id)
+{
+ if (wiegand_module_known(id))
+ return wiegand_module_table[id].name;
+ else
+ return "unknown";
+}
+
+static int wiegand_match(struct device *dev, struct device_driver *drv)
+{
+ struct wiegand_device *wdev = to_wiegand_device(dev);
+ struct wiegand_driver *wdrv = to_wiegand_driver(drv);
+ const enum wiegand_module_id *t;
+
+ if (of_driver_match_device(dev, drv))
+ return 1;
+
+ if (!wdrv->id_table)
+ return 0;
+
+ for (t = wdrv->id_table; *t; ++t)
+ if (*t == wdev->id)
+ return 1;
+
+ return 0;
+}
+
+static struct bus_type wiegand_bus_type = {
+ .name = "wiegand",
+ .match = wiegand_match,
+};
+
+int __wiegand_register_driver(struct module *owner,
+ struct wiegand_driver *wdrv)
+{
+ wdrv->driver.owner = owner;
+ wdrv->driver.bus = &wiegand_bus_type;
+ return driver_register(&wdrv->driver);
+}
+EXPORT_SYMBOL_GPL(__wiegand_register_driver);
+
+static int wiegand_dev_check(struct device *dev, void *data)
+{
+ struct wiegand_device *wdev = to_wiegand_device(dev);
+ struct wiegand_device *new_dev = data;
+
+ if (wdev->wiegand == new_dev->wiegand && wdev->id == new_dev->id &&
+ wdev->idx == new_dev->idx)
+ return -EBUSY;
+ return 0;
+}
+
+static void wiegand_dev_release(struct device *dev)
+{
+ struct wiegand_device *wdev = to_wiegand_device(dev);
+
+ put_device(wdev->wiegand->dev);
+ kfree(wdev);
+}
+
+static struct wiegand_device *
+wiegand_alloc_device(struct wiegand *wiegand)
+{
+ struct wiegand_device *dev;
+
+ if (!get_device(wiegand->dev))
+ return NULL;
+
+ dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+ if (!dev) {
+ put_device(wiegand->dev);
+ return NULL;
+ }
+
+ dev->wiegand = wiegand;
+ dev->dev.parent = wiegand->dev;
+ dev->dev.bus = &wiegand_bus_type;
+ dev->dev.release = wiegand_dev_release;
+
+ device_initialize(&dev->dev);
+
+ return dev;
+}
+
+static int wiegand_add_device(struct wiegand_device *dev)
+{
+ static DEFINE_MUTEX(add_mutex);
+ int ret;
+
+ if (dev->idx >= WIEGAND_MAX_MODULES)
+ return -EINVAL;
+
+ dev_set_name(&dev->dev, "wiegand-%s.%u", wiegand_module_name(dev->id),
+ dev->idx);
+
+ mutex_lock(&add_mutex);
+
+ ret = bus_for_each_dev(&wiegand_bus_type, NULL, dev,
+ wiegand_dev_check);
+ if (ret)
+ goto done;
+
+ ret = device_add(&dev->dev);
+ if (ret < 0)
+ dev_err(dev->wiegand->dev, "Can't add %s, status %d\n",
+ dev_name(dev->wiegand->dev), ret);
+
+done:
+ mutex_unlock(&add_mutex);
+ return ret;
+}
+
+static int __unregister(struct device *dev, void *null)
+{
+ if (dev->of_node)
+ of_node_put(dev->of_node);
+
+ device_unregister(dev);
+
+ return 0;
+}
+
+static struct wiegand_device *
+of_register_wiegand_device(struct wiegand *wiegand, struct device_node *nc)
+{
+ struct wiegand_device *dev;
+ const char *val;
+ int ret;
+
+ dev = wiegand_alloc_device(wiegand);
+ if (!dev) {
+ dev_err(wiegand->dev,
+ "Wiegand device alloc error for %pOF\n", nc);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ ret = of_property_read_string(nc, "compatible", &val);
+ if (ret) {
+ dev_err(wiegand->dev, "%pOF has no valid 'compatible' property (%d)\n",
+ nc, ret);
+ goto err_put;
+ }
+
+ if (strcmp(val, "wiegand,wiegand-gpio") == 0) {
+ dev->idx = 0;
+ dev->id = WIEGAND_MODULE_GPIO;
+ wiegand->modules[0] = dev->id;
+ wiegand->count++;
+ }
+
+ of_node_get(nc);
+ dev->dev.of_node = nc;
+
+ ret = wiegand_add_device(dev);
+ if (ret) {
+ dev_err(wiegand->dev,
+ "Wiegand device register error for %pOF\n", nc);
+ of_node_put(nc);
+ goto err_put;
+ }
+
+ return dev;
+
+err_put:
+ put_device(&dev->dev);
+ return ERR_PTR(ret);
+}
+
+static void of_register_wiegand_devices(struct wiegand *wiegand)
+{
+ struct wiegand_device *dev;
+ struct device_node *nc;
+
+ if (!wiegand->dev->of_node)
+ return;
+
+ for_each_available_child_of_node(wiegand->dev->of_node, nc) {
+ dev = of_register_wiegand_device(wiegand, nc);
+ if (IS_ERR(dev)) {
+ dev_warn(wiegand->dev,
+ "Failed to create Wiegand device for %pOF\n",
+ nc);
+ }
+ }
+}
+
+static int wiegand_probe(struct platform_device *pdev)
+{
+ struct wiegand *wiegand;
+
+ wiegand = devm_kzalloc(&pdev->dev, sizeof(struct wiegand),
+ GFP_KERNEL);
+ if (!wiegand)
+ return -ENOMEM;
+
+ wiegand->dev = &pdev->dev;
+ dev_set_drvdata(&pdev->dev, wiegand);
+
+ mutex_init(&wiegand->lock);
+
+ of_register_wiegand_devices(wiegand);
+
+ return 0;
+}
+
+static int wiegand_remove(struct platform_device *pdev)
+{
+ struct wiegand *wiegand = dev_get_drvdata(&pdev->dev);
+
+ device_for_each_child(&pdev->dev, NULL, __unregister);
+
+ mutex_destroy(&wiegand->lock);
+
+ return 0;
+}
+
+static const struct of_device_id wiegand_dt_ids[] = {
+ { .compatible = "wiegand" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, wiegand_dt_ids);
+
+static struct platform_driver wiegand_driver = {
+ .driver = {
+ .name = "wiegand",
+ .of_match_table = wiegand_dt_ids,
+ },
+ .probe = wiegand_probe,
+ .remove = wiegand_remove,
+};
+
+static int __init wiegand_init(void)
+{
+ int ret;
+
+ ret = bus_register(&wiegand_bus_type);
+ if (ret < 0) {
+ pr_err("Wiegand bus registration failed: %d\n", ret);
+ goto error;
+ }
+
+ ret = platform_driver_register(&wiegand_driver);
+ if (ret < 0) {
+ pr_err("Wiegand driver registration failed: %d\n", ret);
+ goto error_bus;
+ }
+
+ return 0;
+
+error_bus:
+ bus_unregister(&wiegand_bus_type);
+error:
+ return ret;
+}
+postcore_initcall_sync(wiegand_init);
+
+static void __exit wiegand_exit(void)
+{
+ platform_driver_unregister(&wiegand_driver);
+ bus_unregister(&wiegand_bus_type);
+}
+module_exit(wiegand_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Wiegand bus driver");
+MODULE_AUTHOR("Martin Zaťovič <[email protected]>");
diff --git a/include/linux/wiegand.h b/include/linux/wiegand.h
new file mode 100644
index 000000000000..98d8671f042e
--- /dev/null
+++ b/include/linux/wiegand.h
@@ -0,0 +1,110 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef H_LINUX_INCLUDE_LINUX_WIEGAND_H
+#define H_LINUX_INCLUDE_LINUX_WIEGAND_H
+
+#include <linux/device.h>
+#include <linux/mutex.h>
+
+#define WIEGAND_MAX_PAYLEN_BYTES 256
+#define WIEGAND_MAX_MODULES 1
+
+/* The used wiegand format; when data does not end at octet boundaries, the
+ * lower bits of the last octet will be ignored and only the upper ones will be
+ * used.
+ */
+enum wiegand_format {
+ WIEGAND_V26 = 26,
+ WIEGAND_V36 = 36,
+ WIEGAND_V37 = 37,
+ WIEGAND_CUSTOM = 0,
+};
+
+enum wiegand_module_id {
+ WIEGAND_MODULE_FIRST = 0x01,
+ WIEGAND_MODULE_GPIO = 0x01,
+ WIEGAND_MODULE_LAST = 0x01,
+};
+
+enum wiegand_paylen {
+ WIEGAND_V26_PAYLEN = 24,
+ WIEGAND_V36_PAYLEN = 34,
+ WIEGAND_V37_PAYLEN = 35,
+};
+
+extern struct bus_type wiegand_type;
+
+struct wiegand {
+ struct device *dev;
+ struct mutex lock;
+ int count;
+ u8 modules[WIEGAND_MAX_MODULES];
+};
+
+struct wiegand_driver {
+ const enum wiegand_module_id *id_table;
+ struct device_driver driver;
+};
+
+struct wiegand_device {
+ struct device dev;
+ struct wiegand *wiegand;
+ enum wiegand_module_id id;
+ unsigned int idx;
+};
+
+extern int __wiegand_register_driver(struct module *owner,
+ struct wiegand_driver *mdrv);
+
+static inline void wiegand_unregister_driver(struct wiegand_driver *mdrv)
+{
+ if (mdrv)
+ driver_unregister(&mdrv->driver);
+}
+
+#define wiegand_register_driver(driver) \
+ __wiegand_register_driver(THIS_MODULE, driver)
+
+#define module_wiegand_driver(__wiegand_driver) \
+ module_driver(__wiegand_driver, wiegand_register_driver, \
+ wiegand_unregister_driver)
+
+static inline struct wiegand_driver *
+to_wiegand_driver(struct device_driver *drv)
+{
+ if (!drv)
+ return NULL;
+ return container_of(drv, struct wiegand_driver, driver);
+}
+
+static inline struct wiegand_device *
+to_wiegand_device(struct device *dev)
+{
+ if (!dev)
+ return NULL;
+ return container_of(dev, struct wiegand_device, dev);
+}
+
+/**
+ * struct wiegand_setup - Wiegand communication attributes
+ * @pulse_len: length of the low pulse in usec; defaults to 50us
+ * @interval_len: length of a whole bit (both the pulse and the high phase) in
+ * usec; defaults to 2000us
+ * @frame_gap: length of the last bit of a frame (both the pulse and the high
+ * phase) in usec; defaults to interval_len
+ * @format: the used wiegand format
+ * @payload_len: payload of wiegand message in bits
+ */
+struct wiegand_setup {
+ unsigned long pulse_len;
+ unsigned long interval_len;
+ unsigned long frame_gap;
+ enum wiegand_format format;
+ unsigned long payload_len;
+};
+
+extern int wiegand_gpio_calc_parity8(u8 v);
+extern void wiegand_gpio_add_parity_to_data(unsigned char *tmp, u8 *data,
+ enum wiegand_format fmt);
+
+#endif /* H_LINUX_INCLUDE_LINUX_WIEGAND_H */
--
2.37.3
On 05/10/2022 16:57, Martin Zaťovič wrote:
> The Wiegand bus driver spawns devices and matches them with
> drivers.
>
> Signed-off-by: Martin Zaťovič <[email protected]>
> ---
> The bus driver currently assumes that any new Wiegand driver will
> have a matching entry in the devicetree. It is currently sufficient
> as I will only be implementing the GPIO driver. If someone
> implements a Wiegand driver that will not use devicetree, he will
> also have to edit this bus driver, in order to match properly. Is
> that a correct approach?
(...)
> +static struct wiegand_device *
> +of_register_wiegand_device(struct wiegand *wiegand, struct device_node *nc)
> +{
> + struct wiegand_device *dev;
> + const char *val;
> + int ret;
> +
> + dev = wiegand_alloc_device(wiegand);
> + if (!dev) {
> + dev_err(wiegand->dev,
> + "Wiegand device alloc error for %pOF\n", nc);
> + return ERR_PTR(-ENOMEM);
> + }
> +
> + ret = of_property_read_string(nc, "compatible", &val);
> + if (ret) {
> + dev_err(wiegand->dev, "%pOF has no valid 'compatible' property (%d)\n",
> + nc, ret);
> + goto err_put;
> + }
> +
> + if (strcmp(val, "wiegand,wiegand-gpio") == 0) {
This does not look right. Bus can have any device attached, so limiting
some bus behavior to a specific device is not really scalable.
Anyway device and node matching should not be with strcmp but rather
of_*_match().
Best regards,
Krzysztof
On Wed, Oct 5, 2022 at 4:58 PM Martin Zaťovič <[email protected]> wrote:
> The Wiegand bus driver spawns devices and matches them with
> drivers.
>
> Signed-off-by: Martin Zaťovič <[email protected]>
Overall this is a vast improvement over the first patches!
I might not have time to look closer right now, but I see you got
a lot of comments from Krzysztof et al so you have some stuff to
work on.
Looking forward to the first non-RFC patch series!
Yours,
Linus Walleij