firmware: turris-mox-rwtm: Don't create own kobject type

In order to create attribute files in /sys/firmware/turris-mox-rwtm,
this driver creates it's own kobject type.

Simplify this by dropping this own kobject creation, and instead
creating standard device attribute files.

For backwards compatibility with sysfs ABI, create a symlink
/sys/firmware/turris-mox-rwtm, pointing to this device's sysfs
directory.

Signed-off-by: Marek Behún <kabel@kernel.org>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Link: https://lore.kernel.org/r/20240831092050.23093-8-kabel@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

diff --git a/drivers/firmware/turris-mox-rwtm.c b/drivers/firmware/turris-mox-rwtm.c
index 8923c4c..97b4098 100644 (file)
--- a/drivers/firmware/turris-mox-rwtm.c
+++ b/drivers/firmware/turris-mox-rwtm.c
@@ -23,7 +23,6 @@
 #include <linux/mutex.h>
 #include <linux/platform_device.h>
 #include <linux/sizes.h>
-#include <linux/slab.h>
 #include <linux/sysfs.h>
 #include <linux/types.h>
 
@@ -61,13 +60,10 @@ enum mbox_cmd {
        MBOX_CMD_OTP_WRITE      = 8,
 };
 
-struct mox_kobject;
-
 struct mox_rwtm {
        struct device *dev;
        struct mbox_client mbox_client;
        struct mbox_chan *mbox;
-       struct mox_kobject *kobj;
        struct hwrng hwrng;
 
        struct armada_37xx_rwtm_rx_msg reply;
@@ -101,59 +97,17 @@ struct mox_rwtm {
 #endif
 };
 
-struct mox_kobject {
-       struct kobject kobj;
-       struct mox_rwtm *rwtm;
-};
-
-static inline struct kobject *rwtm_to_kobj(struct mox_rwtm *rwtm)
-{
-       return &rwtm->kobj->kobj;
-}
-
-static inline struct mox_rwtm *to_rwtm(struct kobject *kobj)
-{
-       return container_of(kobj, struct mox_kobject, kobj)->rwtm;
-}
-
-static void mox_kobj_release(struct kobject *kobj)
-{
-       kfree(to_rwtm(kobj)->kobj);
-}
-
-static const struct kobj_type mox_kobj_ktype = {
-       .release        = mox_kobj_release,
-       .sysfs_ops      = &kobj_sysfs_ops,
-};
-
-static int mox_kobj_create(struct mox_rwtm *rwtm)
-{
-       rwtm->kobj = kzalloc(sizeof(*rwtm->kobj), GFP_KERNEL);
-       if (!rwtm->kobj)
-               return -ENOMEM;
-
-       kobject_init(rwtm_to_kobj(rwtm), &mox_kobj_ktype);
-       if (kobject_add(rwtm_to_kobj(rwtm), firmware_kobj, "turris-mox-rwtm")) {
-               kobject_put(rwtm_to_kobj(rwtm));
-               return -ENXIO;
-       }
-
-       rwtm->kobj->rwtm = rwtm;
-
-       return 0;
-}
-
 #define MOX_ATTR_RO(name, format, cat)                         \
 static ssize_t                                                 \
-name##_show(struct kobject *kobj, struct kobj_attribute *a,    \
+name##_show(struct device *dev, struct device_attribute *a,    \
            char *buf)                                          \
 {                                                              \
-       struct mox_rwtm *rwtm = to_rwtm(kobj);  \
+       struct mox_rwtm *rwtm = dev_get_drvdata(dev);           \
        if (!rwtm->has_##cat)                                   \
                return -ENODATA;                                \
        return sysfs_emit(buf, format, rwtm->name);             \
 }                                                              \
-static struct kobj_attribute mox_attr_##name = __ATTR_RO(name)
+static DEVICE_ATTR_RO(name)
 
 MOX_ATTR_RO(serial_number, "%016llX\n", board_info);
 MOX_ATTR_RO(board_version, "%i\n", board_info);
@@ -162,6 +116,17 @@ MOX_ATTR_RO(mac_address1, "%pM\n", board_info);
 MOX_ATTR_RO(mac_address2, "%pM\n", board_info);
 MOX_ATTR_RO(pubkey, "%s\n", pubkey);
 
+static struct attribute *turris_mox_rwtm_attrs[] = {
+       &dev_attr_serial_number.attr,
+       &dev_attr_board_version.attr,
+       &dev_attr_ram_size.attr,
+       &dev_attr_mac_address1.attr,
+       &dev_attr_mac_address2.attr,
+       &dev_attr_pubkey.attr,
+       NULL
+};
+ATTRIBUTE_GROUPS(turris_mox_rwtm);
+
 static int mox_get_status(enum mbox_cmd cmd, u32 retval)
 {
        if (MBOX_STS_CMD(retval) != cmd)
@@ -176,16 +141,6 @@ static int mox_get_status(enum mbox_cmd cmd, u32 retval)
                return MBOX_STS_VALUE(retval);
 }
 
-static const struct attribute *mox_rwtm_attrs[] = {
-       &mox_attr_serial_number.attr,
-       &mox_attr_board_version.attr,
-       &mox_attr_ram_size.attr,
-       &mox_attr_mac_address1.attr,
-       &mox_attr_mac_address2.attr,
-       &mox_attr_pubkey.attr,
-       NULL
-};
-
 static void mox_rwtm_rx_callback(struct mbox_client *cl, void *data)
 {
        struct mox_rwtm *rwtm = dev_get_drvdata(cl->dev);
@@ -486,6 +441,11 @@ static inline void rwtm_unregister_debugfs(struct mox_rwtm *rwtm)
 }
 #endif
 
+static void rwtm_firmware_symlink_drop(void *parent)
+{
+       sysfs_remove_link(parent, DRIVER_NAME);
+}
+
 static int turris_mox_rwtm_probe(struct platform_device *pdev)
 {
        struct mox_rwtm *rwtm;
@@ -502,18 +462,6 @@ static int turris_mox_rwtm_probe(struct platform_device *pdev)
        if (!rwtm->buf)
                return -ENOMEM;
 
-       ret = mox_kobj_create(rwtm);
-       if (ret < 0) {
-               dev_err(dev, "Cannot create turris-mox-rwtm kobject!\n");
-               return ret;
-       }
-
-       ret = sysfs_create_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
-       if (ret < 0) {
-               dev_err(dev, "Cannot create sysfs files!\n");
-               goto put_kobj;
-       }
-
        platform_set_drvdata(pdev, rwtm);
 
        mutex_init(&rwtm->busy);
@@ -528,7 +476,7 @@ static int turris_mox_rwtm_probe(struct platform_device *pdev)
                if (ret != -EPROBE_DEFER)
                        dev_err(dev, "Cannot request mailbox channel: %i\n",
                                ret);
-               goto remove_files;
+               return ret;
        }
 
        ret = mox_get_board_info(rwtm);
@@ -560,14 +508,19 @@ static int turris_mox_rwtm_probe(struct platform_device *pdev)
 
        dev_info(dev, "HWRNG successfully registered\n");
 
+       /*
+        * For sysfs ABI compatibility, create symlink
+        * /sys/firmware/turris-mox-rwtm to this device's sysfs directory.
+        */
+       ret = sysfs_create_link(firmware_kobj, &dev->kobj, DRIVER_NAME);
+       if (!ret)
+               devm_add_action_or_reset(dev, rwtm_firmware_symlink_drop,
+                                        firmware_kobj);
+
        return 0;
 
 free_channel:
        mbox_free_channel(rwtm->mbox);
-remove_files:
-       sysfs_remove_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
-put_kobj:
-       kobject_put(rwtm_to_kobj(rwtm));
        return ret;
 }
 
@@ -576,8 +529,6 @@ static void turris_mox_rwtm_remove(struct platform_device *pdev)
        struct mox_rwtm *rwtm = platform_get_drvdata(pdev);
 
        rwtm_unregister_debugfs(rwtm);
-       sysfs_remove_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
-       kobject_put(rwtm_to_kobj(rwtm));
        mbox_free_channel(rwtm->mbox);
 }
 
@@ -595,6 +546,7 @@ static struct platform_driver turris_mox_rwtm_driver = {
        .driver = {
                .name           = DRIVER_NAME,
                .of_match_table = turris_mox_rwtm_match,
+               .dev_groups     = turris_mox_rwtm_groups,
        },
 };
 module_platform_driver(turris_mox_rwtm_driver);