ath25: add back target support

Discussion on the mailing list reveals that this target has active
users. As we are finally able to upgrade this target to kernel 5.4,
add it back to master.

This reverts commit 7d29a5571403 ("ath25: drop target") and
immediately moves the relevant files to 5.4, without touching
the content.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

1 files changed, 111 insertions, 0 deletions

diff --git a/target/linux/ath25/patches-5.4/220-enet_micrel_workaround.patch b/target/linux/ath25/patches-5.4/220-enet_micrel_workaround.patch
new file mode 100644
index 0000000000..91b9792515
--- /dev/null
+++ b/target/linux/ath25/patches-5.4/220-enet_micrel_workaround.patch
@@ -0,0 +1,111 @@
+--- a/drivers/net/ethernet/atheros/ar231x/ar231x.c
++++ b/drivers/net/ethernet/atheros/ar231x/ar231x.c
+@@ -135,6 +135,7 @@ static int ar231x_mdiobus_write(struct m
+ static int ar231x_mdiobus_reset(struct mii_bus *bus);
+ static int ar231x_mdiobus_probe(struct net_device *dev);
+ static void ar231x_adjust_link(struct net_device *dev);
++static bool no_phy;
+ 
+ #ifndef ERR
+ #define ERR(fmt, args...) printk("%s: " fmt, __func__, ##args)
+@@ -167,6 +168,32 @@ static const struct net_device_ops ar231
+ #endif
+ };
+ 
++static int get_phy_id(struct mii_bus *bus, int addr, u32 *phy_id)
++{
++	int phy_reg;
++
++	/**
++	 * Grab the bits from PHYIR1, and put them
++	 * in the upper half.
++	 */
++	phy_reg = mdiobus_read(bus, addr, MII_PHYSID1);
++
++	if (phy_reg < 0)
++		return -EIO;
++
++	*phy_id = (phy_reg & 0xffff) << 16;
++
++	/* Grab the bits from PHYIR2, and put them in the lower half */
++	phy_reg = mdiobus_read(bus, addr, MII_PHYSID2);
++
++	if (phy_reg < 0)
++		return -EIO;
++
++	*phy_id |= (phy_reg & 0xffff);
++
++	return 0;
++}
++
+ static int ar231x_probe(struct platform_device *pdev)
+ {
+ 	struct net_device *dev;
+@@ -273,6 +300,24 @@ static int ar231x_probe(struct platform_
+ 
+ 	mdiobus_register(sp->mii_bus);
+ 
++	/**
++	 * Workaround for Micrel switch, which is only available on
++	 * one PHY and cannot be configured through MDIO.
++	 */
++	if (!no_phy) {
++		u32 phy_id = 0;
++
++		get_phy_id(sp->mii_bus, 1, &phy_id);
++		if (phy_id == 0x00221450)
++			no_phy = true;
++	}
++	if (no_phy) {
++		sp->link = 1;
++		netif_carrier_on(dev);
++		return 0;
++	}
++	no_phy = true;
++
+ 	if (ar231x_mdiobus_probe(dev) != 0) {
+ 		printk(KERN_ERR "%s: mdiobus_probe failed\n", dev->name);
+ 		rx_tasklet_cleanup(dev);
+@@ -326,8 +371,10 @@ static int ar231x_remove(struct platform
+ 	rx_tasklet_cleanup(dev);
+ 	ar231x_init_cleanup(dev);
+ 	unregister_netdev(dev);
+-	mdiobus_unregister(sp->mii_bus);
+-	mdiobus_free(sp->mii_bus);
++	if (sp->mii_bus) {
++		mdiobus_unregister(sp->mii_bus);
++		mdiobus_free(sp->mii_bus);
++	}
+ 	kfree(dev);
+ 	return 0;
+ }
+@@ -870,7 +917,8 @@ static int ar231x_open(struct net_device
+ 
+ 	sp->eth_regs->mac_control |= MAC_CONTROL_RE;
+ 
+-	phy_start(sp->phy_dev);
++	if (sp->phy_dev)
++		phy_start(sp->phy_dev);
+ 
+ 	return 0;
+ }
+@@ -951,7 +999,8 @@ static int ar231x_close(struct net_devic
+ 
+ #endif
+ 
+-	phy_stop(sp->phy_dev);
++	if (sp->phy_dev)
++		phy_stop(sp->phy_dev);
+ 
+ 	return 0;
+ }
+@@ -995,6 +1044,9 @@ static int ar231x_ioctl(struct net_devic
+ {
+ 	struct ar231x_private *sp = netdev_priv(dev);
+ 
++	if (!sp->phy_dev)
++		return -ENODEV;
++
+ 	switch (cmd) {
+ 	case SIOCGMIIPHY:
+ 	case SIOCGMIIREG: