diff options
author | Ben Hoff <hoff.benjamin.k@gmail.com> | 2025-04-29 14:28:09 -0400 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-05-01 17:30:48 +0200 |
commit | ea34925f5b2ee48d7b8b47bc041e381a3cb637cc (patch) | |
tree | 3cb9d547b39bf1af1aed7d8c59e02194aca7a868 | |
parent | 3fc0810497a697b84dfe36f6011bd04c5e21d39b (diff) |
usb: gadget: hid: allow dynamic interval configuration via configfs
This patch enhances the HID gadget driver to support dynamic configuration
of the interrupt polling interval (bInterval) via configfs. A new
‘interval’ attribute is exposed under each HID function’s configfs
directory, and any write to it will adjust the poll rate for all endpoints
without requiring a rebuild.
When the attribute has never been written, legacy defaults are preserved:
• Full-Speed (FS) endpoints (IN & OUT) poll every 10 ms
• High-Speed (HS) endpoints (IN & OUT) poll every 4 micro-frames
(~1 ms)
To implement this cleanly:
• Add two new fields to f_hid_opts and f_hidg:
– unsigned char interval
– bool interval_user_set
• Introduce dedicated f_hid_opts_interval_show/store functions.
The store routine parses into an unsigned int, bounds‐checks,
assigns to opts->interval, and sets opts->interval_user_set = true.
• Initialize opts->interval = 4 and opts->interval_user_set = false in
hidg_alloc_inst(), then copy both into the live f_hidg instance in
hidg_alloc().
• In hidg_bind(), set each endpoint’s bInterval based on whether the
user has written the attribute:
– If interval_user_set == false, use FS=10 / HS=4
– If interval_user_set == true, use the user’s value for both FS
& HS
Signed-off-by: Ben Hoff <hoff.benjamin.k@gmail.com>
Link: https://lore.kernel.org/r/20250429182809.811786-1-hoff.benjamin.k@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | drivers/usb/gadget/function/f_hid.c | 119 | ||||
-rw-r--r-- | drivers/usb/gadget/function/u_hid.h | 2 |
2 files changed, 90 insertions, 31 deletions
diff --git a/drivers/usb/gadget/function/f_hid.c b/drivers/usb/gadget/function/f_hid.c index 1bc40fc0ccf7..1b2a363f3177 100644 --- a/drivers/usb/gadget/function/f_hid.c +++ b/drivers/usb/gadget/function/f_hid.c @@ -62,6 +62,9 @@ struct f_hidg { unsigned short report_desc_length; char *report_desc; unsigned short report_length; + unsigned char interval; + bool interval_user_set; + /* * use_out_ep - if true, the OUT Endpoint (interrupt out method) * will be used to receive reports from the host @@ -157,10 +160,7 @@ static struct usb_endpoint_descriptor hidg_ss_in_ep_desc = { .bEndpointAddress = USB_DIR_IN, .bmAttributes = USB_ENDPOINT_XFER_INT, /*.wMaxPacketSize = DYNAMIC */ - .bInterval = 4, /* FIXME: Add this field in the - * HID gadget configuration? - * (struct hidg_func_descriptor) - */ + /*.bInterval = DYNAMIC */ }; static struct usb_ss_ep_comp_descriptor hidg_ss_in_comp_desc = { @@ -178,10 +178,7 @@ static struct usb_endpoint_descriptor hidg_ss_out_ep_desc = { .bEndpointAddress = USB_DIR_OUT, .bmAttributes = USB_ENDPOINT_XFER_INT, /*.wMaxPacketSize = DYNAMIC */ - .bInterval = 4, /* FIXME: Add this field in the - * HID gadget configuration? - * (struct hidg_func_descriptor) - */ + /*.bInterval = DYNAMIC */ }; static struct usb_ss_ep_comp_descriptor hidg_ss_out_comp_desc = { @@ -219,10 +216,7 @@ static struct usb_endpoint_descriptor hidg_hs_in_ep_desc = { .bEndpointAddress = USB_DIR_IN, .bmAttributes = USB_ENDPOINT_XFER_INT, /*.wMaxPacketSize = DYNAMIC */ - .bInterval = 4, /* FIXME: Add this field in the - * HID gadget configuration? - * (struct hidg_func_descriptor) - */ + /* .bInterval = DYNAMIC */ }; static struct usb_endpoint_descriptor hidg_hs_out_ep_desc = { @@ -231,10 +225,7 @@ static struct usb_endpoint_descriptor hidg_hs_out_ep_desc = { .bEndpointAddress = USB_DIR_OUT, .bmAttributes = USB_ENDPOINT_XFER_INT, /*.wMaxPacketSize = DYNAMIC */ - .bInterval = 4, /* FIXME: Add this field in the - * HID gadget configuration? - * (struct hidg_func_descriptor) - */ + /*.bInterval = DYNAMIC */ }; static struct usb_descriptor_header *hidg_hs_descriptors_intout[] = { @@ -260,10 +251,7 @@ static struct usb_endpoint_descriptor hidg_fs_in_ep_desc = { .bEndpointAddress = USB_DIR_IN, .bmAttributes = USB_ENDPOINT_XFER_INT, /*.wMaxPacketSize = DYNAMIC */ - .bInterval = 10, /* FIXME: Add this field in the - * HID gadget configuration? - * (struct hidg_func_descriptor) - */ + /*.bInterval = DYNAMIC */ }; static struct usb_endpoint_descriptor hidg_fs_out_ep_desc = { @@ -272,10 +260,7 @@ static struct usb_endpoint_descriptor hidg_fs_out_ep_desc = { .bEndpointAddress = USB_DIR_OUT, .bmAttributes = USB_ENDPOINT_XFER_INT, /*.wMaxPacketSize = DYNAMIC */ - .bInterval = 10, /* FIXME: Add this field in the - * HID gadget configuration? - * (struct hidg_func_descriptor) - */ + /*.bInterval = DYNAMIC */ }; static struct usb_descriptor_header *hidg_fs_descriptors_intout[] = { @@ -1217,6 +1202,16 @@ static int hidg_bind(struct usb_configuration *c, struct usb_function *f) hidg_hs_in_ep_desc.wMaxPacketSize = cpu_to_le16(hidg->report_length); hidg_fs_in_ep_desc.wMaxPacketSize = cpu_to_le16(hidg->report_length); hidg_ss_out_ep_desc.wMaxPacketSize = cpu_to_le16(hidg->report_length); + + /* IN endpoints: FS default=10ms, HS default=4µ-frame; user override if set */ + if (!hidg->interval_user_set) { + hidg_fs_in_ep_desc.bInterval = 10; + hidg_hs_in_ep_desc.bInterval = 4; + } else { + hidg_fs_in_ep_desc.bInterval = hidg->interval; + hidg_hs_in_ep_desc.bInterval = hidg->interval; + } + hidg_ss_out_comp_desc.wBytesPerInterval = cpu_to_le16(hidg->report_length); hidg_hs_out_ep_desc.wMaxPacketSize = cpu_to_le16(hidg->report_length); @@ -1239,19 +1234,27 @@ static int hidg_bind(struct usb_configuration *c, struct usb_function *f) hidg_ss_out_ep_desc.bEndpointAddress = hidg_fs_out_ep_desc.bEndpointAddress; - if (hidg->use_out_ep) + if (hidg->use_out_ep) { + /* OUT endpoints: same defaults (FS=10, HS=4) unless user set */ + if (!hidg->interval_user_set) { + hidg_fs_out_ep_desc.bInterval = 10; + hidg_hs_out_ep_desc.bInterval = 4; + } else { + hidg_fs_out_ep_desc.bInterval = hidg->interval; + hidg_hs_out_ep_desc.bInterval = hidg->interval; + } status = usb_assign_descriptors(f, - hidg_fs_descriptors_intout, - hidg_hs_descriptors_intout, - hidg_ss_descriptors_intout, - hidg_ss_descriptors_intout); - else + hidg_fs_descriptors_intout, + hidg_hs_descriptors_intout, + hidg_ss_descriptors_intout, + hidg_ss_descriptors_intout); + } else { status = usb_assign_descriptors(f, hidg_fs_descriptors_ssreport, hidg_hs_descriptors_ssreport, hidg_ss_descriptors_ssreport, hidg_ss_descriptors_ssreport); - + } if (status) goto fail; @@ -1423,6 +1426,53 @@ end: CONFIGFS_ATTR(f_hid_opts_, report_desc); +static ssize_t f_hid_opts_interval_show(struct config_item *item, char *page) +{ + struct f_hid_opts *opts = to_f_hid_opts(item); + int result; + + mutex_lock(&opts->lock); + result = sprintf(page, "%d\n", opts->interval); + mutex_unlock(&opts->lock); + + return result; +} + +static ssize_t f_hid_opts_interval_store(struct config_item *item, + const char *page, size_t len) +{ + struct f_hid_opts *opts = to_f_hid_opts(item); + int ret; + unsigned int tmp; + + mutex_lock(&opts->lock); + if (opts->refcnt) { + ret = -EBUSY; + goto end; + } + + /* parse into a wider type first */ + ret = kstrtouint(page, 0, &tmp); + if (ret) + goto end; + + /* range-check against unsigned char max */ + if (tmp > 255) { + ret = -EINVAL; + goto end; + } + + opts->interval = (unsigned char)tmp; + opts->interval_user_set = true; + ret = len; + +end: + mutex_unlock(&opts->lock); + return ret; +} + +CONFIGFS_ATTR(f_hid_opts_, interval); + static ssize_t f_hid_opts_dev_show(struct config_item *item, char *page) { struct f_hid_opts *opts = to_f_hid_opts(item); @@ -1437,6 +1487,7 @@ static struct configfs_attribute *hid_attrs[] = { &f_hid_opts_attr_protocol, &f_hid_opts_attr_no_out_endpoint, &f_hid_opts_attr_report_length, + &f_hid_opts_attr_interval, &f_hid_opts_attr_report_desc, &f_hid_opts_attr_dev, NULL, @@ -1483,6 +1534,10 @@ static struct usb_function_instance *hidg_alloc_inst(void) if (!opts) return ERR_PTR(-ENOMEM); mutex_init(&opts->lock); + + opts->interval = 4; + opts->interval_user_set = false; + opts->func_inst.free_func_inst = hidg_free_inst; ret = &opts->func_inst; @@ -1561,6 +1616,8 @@ static struct usb_function *hidg_alloc(struct usb_function_instance *fi) hidg->bInterfaceProtocol = opts->protocol; hidg->report_length = opts->report_length; hidg->report_desc_length = opts->report_desc_length; + hidg->interval = opts->interval; + hidg->interval_user_set = opts->interval_user_set; if (opts->report_desc) { hidg->report_desc = kmemdup(opts->report_desc, opts->report_desc_length, diff --git a/drivers/usb/gadget/function/u_hid.h b/drivers/usb/gadget/function/u_hid.h index 84bb70292855..a9ed9720caee 100644 --- a/drivers/usb/gadget/function/u_hid.h +++ b/drivers/usb/gadget/function/u_hid.h @@ -25,6 +25,8 @@ struct f_hid_opts { unsigned short report_desc_length; unsigned char *report_desc; bool report_desc_alloc; + unsigned char interval; + bool interval_user_set; /* * Protect the data form concurrent access by read/write |