net: sfp: VSOL V2801F / CarlitoxxPro CPGOS03-0490 v2.0 workaround

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>

diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
index 34aa196..91d74c1 100644 (file)
--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -219,6 +219,7 @@ 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 *);
@@ -335,10 +336,19 @@ static int sfp_i2c_read(struct sfp *sfp, bool a2, u8 dev_addr, void *buf,
                        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;
@@ -350,8 +360,8 @@ static int sfp_i2c_read(struct sfp *sfp, bool a2, u8 dev_addr, void *buf,
 
        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;
 
@@ -1632,6 +1642,28 @@ static int sfp_sm_mod_hpower(struct sfp *sfp, bool enable)
        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_cotsworks_fixup_check(struct sfp *sfp, struct sfp_eeprom_id *id)
 {
        u8 check;
@@ -1673,14 +1705,20 @@ static int sfp_sm_mod_probe(struct sfp *sfp, bool report)
        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;
        }
@@ -1719,6 +1757,21 @@ static int sfp_sm_mod_probe(struct sfp *sfp, bool report)
                }
        }
 
+       /* 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) {