kernel: backport workaround for Realtek RTL8672 and RTL9601C chips

Adds support for GPON SFP modules based on the Realtek RTL8672 and
RTL9601C chips, including but not limited to:
* V-SOL V2801F
* C-Data FD511GX-RM0
* OPTON GP801R
* BAUDCOM BD-1234-SFM
* CPGOS03-0490 v2.0
* Ubiquiti U-Fiber Instant
* EXOT EGS1

Signed-off-by: Vladimir Markovets <abam_a@yahoo.com>

1 files changed, 144 insertions, 0 deletions

diff --git a/target/linux/generic/backport-5.4/852-v5.10-0001-net-sfp-VSOL-V2801F-CarlitoxxPro-CPGOS03-0490-v2.0-w.patch b/target/linux/generic/backport-5.4/852-v5.10-0001-net-sfp-VSOL-V2801F-CarlitoxxPro-CPGOS03-0490-v2.0-w.patch
new file mode 100644
index 0000000000..1901054a10
--- /dev/null
+++ b/target/linux/generic/backport-5.4/852-v5.10-0001-net-sfp-VSOL-V2801F-CarlitoxxPro-CPGOS03-0490-v2.0-w.patch
@@ -0,0 +1,144 @@
+From 0d035bed2a4a6c4878518749348be61bf082d12a Mon Sep 17 00:00:00 2001
+From: Russell King <rmk+kernel@armlinux.org.uk>
+Date: Wed, 9 Dec 2020 11:22:49 +0000
+Subject: [PATCH] net: sfp: VSOL V2801F / CarlitoxxPro CPGOS03-0490 v2.0
+ workaround
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Add a workaround for the detection of VSOL V2801F / CarlitoxxPro
+CPGOS03-0490 v2.0 GPON module which CarlitoxxPro states needs single
+byte I2C reads to the EEPROM.
+
+Pali Rohár reports that he also has a CarlitoxxPro-based V2801F module,
+which reports a manufacturer of "OEM". This manufacturer can't be
+matched as it appears in many different modules, so also match the part
+number too.
+
+Reported-by: Thomas Schreiber <tschreibe@gmail.com>
+Reported-by: Pali Rohár <pali@kernel.org>
+Tested-by: Pali Rohár <pali@kernel.org>
+Reviewed-by: Andrew Lunn <andrew@lunn.ch>
+Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+---
+ drivers/net/phy/sfp.c | 63 +++++++++++++++++++++++++++++++++++++++----
+ 1 file changed, 58 insertions(+), 5 deletions(-)
+
+--- a/drivers/net/phy/sfp.c
++++ b/drivers/net/phy/sfp.c
+@@ -191,6 +191,7 @@ struct sfp {
+ 	struct sfp_bus *sfp_bus;
+ 	struct phy_device *mod_phy;
+ 	const struct sff_data *type;
++	size_t i2c_block_size;
+ 	u32 max_power_mW;
+ 
+ 	unsigned int (*get_state)(struct sfp *);
+@@ -305,10 +306,19 @@ static int sfp_i2c_read(struct sfp *sfp,
+ 			size_t len)
+ {
+ 	struct i2c_msg msgs[2];
+-	u8 bus_addr = a2 ? 0x51 : 0x50;
++	size_t block_size;
+ 	size_t this_len;
++	u8 bus_addr;
+ 	int ret;
+ 
++	if (a2) {
++		block_size = 16;
++		bus_addr = 0x51;
++	} else {
++		block_size = sfp->i2c_block_size;
++		bus_addr = 0x50;
++	}
++
+ 	msgs[0].addr = bus_addr;
+ 	msgs[0].flags = 0;
+ 	msgs[0].len = 1;
+@@ -320,8 +330,8 @@ static int sfp_i2c_read(struct sfp *sfp,
+ 
+ 	while (len) {
+ 		this_len = len;
+-		if (this_len > 16)
+-			this_len = 16;
++		if (this_len > block_size)
++			this_len = block_size;
+ 
+ 		msgs[1].len = this_len;
+ 
+@@ -1569,6 +1579,28 @@ static int sfp_sm_mod_hpower(struct sfp
+ 	return 0;
+ }
+ 
++/* Some modules (Nokia 3FE46541AA) lock up if byte 0x51 is read as a
++ * single read. Switch back to reading 16 byte blocks unless we have
++ * a CarlitoxxPro module (rebranded VSOL V2801F). Even more annoyingly,
++ * some VSOL V2801F have the vendor name changed to OEM.
++ */
++static int sfp_quirk_i2c_block_size(const struct sfp_eeprom_base *base)
++{
++	if (!memcmp(base->vendor_name, "VSOL            ", 16))
++		return 1;
++	if (!memcmp(base->vendor_name, "OEM             ", 16) &&
++	    !memcmp(base->vendor_pn,   "V2801F          ", 16))
++		return 1;
++
++	/* Some modules can't cope with long reads */
++	return 16;
++}
++
++static void sfp_quirks_base(struct sfp *sfp, const struct sfp_eeprom_base *base)
++{
++	sfp->i2c_block_size = sfp_quirk_i2c_block_size(base);
++}
++
+ static int sfp_sm_mod_probe(struct sfp *sfp, bool report)
+ {
+ 	/* SFP module inserted - read I2C data */
+@@ -1577,14 +1609,20 @@ static int sfp_sm_mod_probe(struct sfp *
+ 	u8 check;
+ 	int ret;
+ 
+-	ret = sfp_read(sfp, false, 0, &id, sizeof(id));
++	/* Some modules (CarlitoxxPro CPGOS03-0490) do not support multibyte
++	 * reads from the EEPROM, so start by reading the base identifying
++	 * information one byte at a time.
++	 */
++	sfp->i2c_block_size = 1;
++
++	ret = sfp_read(sfp, false, 0, &id.base, sizeof(id.base));
+ 	if (ret < 0) {
+ 		if (report)
+ 			dev_err(sfp->dev, "failed to read EEPROM: %d\n", ret);
+ 		return -EAGAIN;
+ 	}
+ 
+-	if (ret != sizeof(id)) {
++	if (ret != sizeof(id.base)) {
+ 		dev_err(sfp->dev, "EEPROM short read: %d\n", ret);
+ 		return -EAGAIN;
+ 	}
+@@ -1612,6 +1650,21 @@ static int sfp_sm_mod_probe(struct sfp *
+ 		}
+ 	}
+ 
++	/* Apply any early module-specific quirks */
++	sfp_quirks_base(sfp, &id.base);
++
++	ret = sfp_read(sfp, false, SFP_CC_BASE + 1, &id.ext, sizeof(id.ext));
++	if (ret < 0) {
++		if (report)
++			dev_err(sfp->dev, "failed to read EEPROM: %d\n", ret);
++		return -EAGAIN;
++	}
++
++	if (ret != sizeof(id.ext)) {
++		dev_err(sfp->dev, "EEPROM short read: %d\n", ret);
++		return -EAGAIN;
++	}
++
+ 	check = sfp_check(&id.ext, sizeof(id.ext) - 1);
+ 	if (check != id.ext.cc_ext) {
+ 		if (cotsworks) {