ppp: Add target-specific patch for Broadcom's accelerator.

Add patch to allow the blog accelerator to work correctly when using PPPoE/PPPoA.

package/network/services/ppp/patches/brcmbca/900-bcmnet_path_update.patch

+--- a/pppd/sys-linux.c	2021-12-15 14:42:59.958193562 +0100
++++ b/pppd/sys-linux.c	2022-02-15 13:12:20.963825923 +0100
+@@ -630,6 +630,91 @@
+     }
+ }
+ 
++typedef struct mac_limit_arg{
++    uint32_t cmd;
++    uint32_t val;
++    union {
++        void *mac_limit;
++        char rsvd[8];
++    };
++}mac_limit_arg_t;
++
++enum mac_limit_cmd{
++    MAC_LIMIT_IOCTL_GET = 0,
++    MAC_LIMIT_IOCTL_SET,
++    MAC_LIMIT_IOCTL_CLR,
++    MAC_LIMIT_IOCTL_EN
++};
++
++enum mac_limit_set_op{
++    MAC_LIMIT_SET_MAX = 0,
++    MAC_LIMIT_SET_MIN,
++};
++
++/*------------------------------------------------------------------------*/
++/* BCM net character device for ioctl to get/set netdev BRCM private info */
++/*------------------------------------------------------------------------*/
++#define BCMNET_DRV_MAJOR            377
++#define BCMNET_DRV_NAME             "bcmnet"
++#define BCMNET_DRV_DEVICE_NAME      "/dev/" BCMNET_DRV_NAME
++
++typedef enum bcmnet_ioctl_cmd
++{
++    BCMNET_IOCTL_GET_EXT_FLAGS,
++    BCMNET_IOCTL_GET_LAST_CHANGE,
++    BCMNET_IOCTL_CLR_STATS,
++    BCMNET_IOCTL_ADD_NETDEV_PATH,
++    BCMNET_IOCTL_MAC_LIMIT,
++    BCMNET_IOCTL_MAX
++} bcmnet_ioctl_cmd_t;
++
++typedef struct {
++    unsigned int unused : 25;
++    unsigned int is_bcm_dev : 1;
++    unsigned int is_wlan : 1;
++    unsigned int is_hw_switch : 1;
++    unsigned int is_hw_fdb : 1;
++    unsigned int is_ppp : 1;
++    unsigned int is_vlan : 1;
++    unsigned int is_wan : 1;
++} bcmnet_extflags;
++
++typedef struct {
++    char if_name[IFNAMSIZ];
++    union {
++        struct {
++            bcmnet_extflags ret_val;
++        }st_get_ext_flags;
++        struct {
++            unsigned long last_change;
++        }st_get_last_change;
++        struct {
++            char next_if_name[IFNAMSIZ];
++        }st_add_netdev_path;
++        mac_limit_arg_t st_mac_limit;
++    };
++}bcmnet_info_t;
++
++#define FIELD0    4        /* ppp device number ppp0, ppp1, the third digit (max 16) */
++#define FIELD1    8        /* if 0, default mode, 1 vlan mux, 2 msc */    
++#define FIELD2    19       /* if FILED1 is 0, add no extension, 1 add vlan id, 2 add conId for msc */
++
++static inline int bcmnet_ioctl_add_netdev_path(char const* dev_name, char const* next_dev_name)
++{
++	bcmnet_info_t info;
++	int fd, err;
++
++	fd = open(BCMNET_DRV_DEVICE_NAME, O_RDWR);
++	if (fd < 0)
++		return -1;
++
++	strncpy(info.if_name, dev_name, IFNAMSIZ);
++	strncpy(info.st_add_netdev_path.next_if_name, next_dev_name, IFNAMSIZ);
++	err = ioctl(fd, BCMNET_IOCTL_ADD_NETDEV_PATH, &info);
++	close(fd);
++	return err;
++}
++
+ /*
+  * make_ppp_unit - make a new ppp unit for ppp_dev_fd.
+  * Assumes new_style_driver.
+@@ -637,6 +722,12 @@
+ static int make_ppp_unit()
+ {
+ 	int x, flags;
++#if 0
++	/* brcm */
++	unsigned num[3] = {0, 0, 0};
++	 char *p;
++	/*end brcm */
++#endif
+ 
+ 	if (ppp_dev_fd >= 0) {
+ 		dbglog("in make_ppp_unit, already had /dev/ppp open?");
+@@ -650,6 +741,40 @@
+ 	    || fcntl(ppp_dev_fd, F_SETFL, flags | O_NONBLOCK) == -1)
+ 		warn("Couldn't set /dev/ppp to nonblock: %m");
+ 
++#if 0
++	 /* brcm */
++	/* req_name will beused as ifname and  for
++	 * num[1] == 0:  default connection mdoe: ppp0, ppp1...
++	 * num[1] == 1:  vlanMux mode: ppp0.100, ppp1.200...  
++	 * num[1] == 2:  msc (multiple service mode) ppp0_1, ppp1_3...
++	 * num[1] == 3:  pppoa0, pppoa1...
++	 *
++	 */
++	if ((p = strchr(req_ifname, '.')) != NULL)
++	{
++		/* vlan mux mode */
++		sscanf(&(req_ifname[3]), "%d.%d", num, num+2);
++		num[1] = 1;
++	}
++	else if ((p = strchr(req_ifname, '_')) != NULL)
++	{
++		/* msc mode */
++		sscanf(&(req_ifname[3]), "%d_%d", num, num+2);
++		num[1] = 2;
++	}
++	else if ((p = strstr(req_ifname, "pppoa")) != NULL)
++	{
++		/* pppoa */
++		num[0] = atoi(&req_ifname[5]);
++		num[1] = 3;
++	}
++	else /* must be default mode */
++	{
++		num[0] = atoi(&req_ifname[3]);
++	}
++	req_unit =  num[0]<<(FIELD1+FIELD2) | num[1]<<FIELD2 | num[2];
++#endif
++
+ 	ifunit = req_unit;
+ 	x = ioctl(ppp_dev_fd, PPPIOCNEWUNIT, &ifunit);
+ 	if (x < 0 && req_unit >= 0 && errno == EEXIST) {
+@@ -674,6 +799,10 @@
+ 		    info("Renamed interface %s to %s", t, req_ifname);
+ 	}
+ 
++	if (bcmnet_ioctl_add_netdev_path(req_ifname, devnam) < 0) {
++		error("Couldn't set ppp real device (%s): %m", devnam);
++	}
++
+ 	return x;
+ }
+