@@ -1130,6 +1130,8 @@ int serial8250_register_8250_port(const struct uart_8250_port *up)
uart->port.pm = up->port.pm;
if (up->port.handle_break)
uart->port.handle_break = up->port.handle_break;
+ if (up->port.attr_group)
+ uart->port.attr_group = up->port.attr_group;
if (up->dl_read)
uart->dl_read = up->dl_read;
if (up->dl_write)
@@ -1210,6 +1212,13 @@ void serial8250_unregister_port(int line)
uart->port.type = PORT_UNKNOWN;
uart->port.dev = &serial8250_isa_devs->dev;
uart->port.port_id = line;
+
+ if (uart->port.attr_group_allocated) {
+ kfree(uart->port.attr_group->attrs);
+ kfree(uart->port.attr_group);
+ uart->port.attr_group_allocated = false;
+ }
+ uart->port.attr_group = NULL;
uart->capabilities = 0;
serial8250_init_port(uart);
serial8250_apply_quirks(uart);
@@ -3135,9 +3135,31 @@ static struct attribute_group serial8250_dev_attr_group = {
static void register_dev_spec_attr_grp(struct uart_8250_port *up)
{
const struct serial8250_config *conf_type = &uart_config[up->port.type];
+ struct attribute **upp_attrs = NULL;
+ int upp_attrs_num = 0, i;
- if (conf_type->rxtrig_bytes[0])
- up->port.attr_group = &serial8250_dev_attr_group;
+ up->port.attr_group_allocated = false;
+
+ if (up->port.attr_group) {
+ upp_attrs = up->port.attr_group->attrs;
+
+ while (upp_attrs[upp_attrs_num])
+ upp_attrs_num++;
+
+ up->port.attr_group = kcalloc(1, sizeof(struct attribute_group), GFP_KERNEL);
+ up->port.attr_group->attrs = kcalloc(upp_attrs_num + 2, sizeof(struct attribute *), GFP_KERNEL);
+
+ for (i = 0; i < upp_attrs_num; ++i)
+ up->port.attr_group->attrs[i] = upp_attrs[i];
+
+ if (conf_type->rxtrig_bytes[0])
+ up->port.attr_group->attrs[upp_attrs_num] = &dev_attr_rx_trig_bytes.attr;
+
+ up->port.attr_group_allocated = true;
+ } else {
+ if (conf_type->rxtrig_bytes[0])
+ up->port.attr_group = &serial8250_dev_attr_group;
+ }
}
static void serial8250_config_port(struct uart_port *port, int flags)
@@ -581,6 +581,7 @@ struct uart_port {
unsigned char console_reinit;
const char *name; /* port name */
struct attribute_group *attr_group; /* port specific attributes */
+ bool attr_group_allocated; /* whether attr_group is dynamic allocated */
const struct attribute_group **tty_groups; /* all attributes (serial core use only) */
struct serial_rs485 rs485;
struct serial_rs485 rs485_supported; /* Supported mask for serial_rs485 */
Many low-level drivers in Linux kernel register their serial ports with the help of universal driver (8250_core, 8250_port). There is an attribute group called `serial8250_dev_attr_group` within `8250_port.c` to handle the `rx_trig_bytes` attribute: https://lore.kernel.org/all/20140716011931.31474.68825.stgit@yuno-kbuild.novalocal/ However, if a low-level driver has some HW specifications that need to be set or retrieved using an attr_group, the universal driver (8250_port) would overwrite the low-level driver's attr_group. This patch allows the low-level driver's attr_group to be passed to the universal driver (8250_port) and combines the two attr_groups. This ensures that the corresponding system file will only be created if the device is registered by such a low-level driver. Signed-off-by: CrescentCY Hsieh <crescentcy.hsieh@moxa.com> --- drivers/tty/serial/8250/8250_core.c | 9 +++++++++ drivers/tty/serial/8250/8250_port.c | 26 ++++++++++++++++++++++++-- include/linux/serial_core.h | 1 + 3 files changed, 34 insertions(+), 2 deletions(-)