[src/trunk]: src/sys/dev Add code to select page "0" for DDR4 and newer SPD R...

[msaitoh <msaitoh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/756cdd99f29e
branches:  trunk
changeset: 347649:756cdd99f29e
user:      msaitoh <msaitoh%NetBSD.org@localhost>
date:      Fri Sep 09 05:36:59 2016 +0000

description:
Add code to select page "0" for DDR4 and newer SPD ROM. If the value read
is not suitable as SPD ROM, try to select page 0 and try again. The passed
arguments of iic_exec(SPDCTL_SPA) might not be correct and/or our API of
iic_exec() should be improved. See the comment for the detail.

Use this change until we find a better (or correct?) way.

diffstat:

 sys/dev/i2c/spdmem_i2c.c |  82 ++++++++++++++++++++++++++++++++++++++++++++++-
 sys/dev/ic/spdmem.c      |  11 ++++--
 2 files changed, 87 insertions(+), 6 deletions(-)

diffs (156 lines):

diff -r a3f08d36069a -r 756cdd99f29e sys/dev/i2c/spdmem_i2c.c
--- a/sys/dev/i2c/spdmem_i2c.c  Thu Sep 08 21:33:56 2016 +0000
+++ b/sys/dev/i2c/spdmem_i2c.c  Fri Sep 09 05:36:59 2016 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: spdmem_i2c.c,v 1.12 2016/01/05 11:49:32 msaitoh Exp $ */
+/* $NetBSD: spdmem_i2c.c,v 1.13 2016/09/09 05:36:59 msaitoh Exp $ */
 
 /*
  * Copyright (c) 2007 Nicolas Joly
@@ -40,7 +40,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: spdmem_i2c.c,v 1.12 2016/01/05 11:49:32 msaitoh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: spdmem_i2c.c,v 1.13 2016/09/09 05:36:59 msaitoh Exp $");
 
 #include <sys/param.h>
 #include <sys/device.h>
@@ -88,6 +88,7 @@
        i2c_addr_t sc_page1;
 };
 
+static int  spdmem_reset_page(struct spdmem_i2c_softc *);
 static int  spdmem_i2c_match(device_t, cfdata_t, void *);
 static void spdmem_i2c_attach(device_t, device_t, void *);
 static int  spdmem_i2c_detach(device_t, int);
@@ -98,6 +99,79 @@
 static int spdmem_i2c_read(struct spdmem_softc *, uint16_t, uint8_t *);
 
 static int
+spdmem_reset_page(struct spdmem_i2c_softc *sc)
+{
+       uint8_t reg, byte0, byte2;
+       int rv;
+
+       reg = 0;
+
+       iic_acquire_bus(sc->sc_tag, 0);
+
+       /*
+        * Try to read byte 0 and 2. If it failed, it's not spdmem or a device
+        * doesn't exist at the address.
+        */
+       rv = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP, sc->sc_addr, &reg, 1,
+           &byte0, 1, I2C_F_POLL);
+       rv |= iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP, sc->sc_addr, &reg, 1,
+           &byte2, 1, I2C_F_POLL);
+       if (rv != 0)
+               goto error;
+
+       /*
+        * Quirk for BIOSes that leave page 1 of a 4kbit EEPROM selected.
+        *
+        * byte0 is the length, byte2 is the memory type. Both of them should
+        * not be zero. If zero, the current page might be 1 (DDR4 and newer).
+        * If page 1 is selected, offset 0 can be 0 (Module Characteristics
+        * (Energy backup is not available)) and also offset 2 can be 0
+        * (Megabytes, and a part of Capacity digits).
+        *
+        * Note: The encoding of byte0 is vary in memory type, so we check
+        * just with zero to be simple.
+        *
+        * Try to see if we are not at page 0. If it's not, select page 0.
+        */
+       if ((byte0 == 0) || (byte2 == 0)) {
+               /*
+                * Note that SDCTL_RPA is the same as sc->sc_page0(SPDCTL_SPA0)
+                * Write is SPA0, read is RPA.
+                *
+                * This call returns 0 on page 0 and returns -1 on page 1.
+                * I don't know whether our icc_exec()'s API is good or not.
+                */
+               rv = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP, sc->sc_page0,
+                   &reg, 1, NULL, 0, I2C_F_POLL);
+               if (rv != 0) {
+                       /*
+                        * The possibilities are:
+                        * a) page 1 is selected.
+                        * b) The device doesn't support page select and
+                        *    it's not a SPD ROM.
+                        * Is there no way to distinguish them now?
+                        */
+                       rv = iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP,
+                           sc->sc_page0, &reg, 1, NULL, 0, I2C_F_POLL);
+                       if (rv == 0) {
+                               aprint_debug("Page 1 was selected. Page 0 is "
+                                   "selected now.\n");
+                       } else {
+                               aprint_debug("Failed to select page 0. This "
+                                   "device isn't SPD ROM\n");
+                       }
+               } else {
+                       /* This device isn't SPD ROM */
+                       rv = -1;
+               }
+       }
+error:
+       iic_release_bus(sc->sc_tag, 0);
+
+       return rv;
+}
+
+static int
 spdmem_i2c_match(device_t parent, cfdata_t match, void *aux)
 {
        struct i2c_attach_args *ia = aux;
@@ -122,6 +196,10 @@
        sc.sc_page1 = SPDCTL_SPA1;
        sc.sc_base.sc_read = spdmem_i2c_read;
 
+       /* Check the bank and reset to the page 0 */
+       if (spdmem_reset_page(&sc) != 0)
+               return 0;
+
        return spdmem_common_probe(&sc.sc_base);
 }
 
diff -r a3f08d36069a -r 756cdd99f29e sys/dev/ic/spdmem.c
--- a/sys/dev/ic/spdmem.c       Thu Sep 08 21:33:56 2016 +0000
+++ b/sys/dev/ic/spdmem.c       Fri Sep 09 05:36:59 2016 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: spdmem.c,v 1.21 2016/01/05 11:49:32 msaitoh Exp $ */
+/* $NetBSD: spdmem.c,v 1.22 2016/09/09 05:36:59 msaitoh Exp $ */
 
 /*
  * Copyright (c) 2007 Nicolas Joly
@@ -35,7 +35,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: spdmem.c,v 1.21 2016/01/05 11:49:32 msaitoh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: spdmem.c,v 1.22 2016/09/09 05:36:59 msaitoh Exp $");
 
 #include <sys/param.h>
 #include <sys/device.h>
@@ -185,6 +185,10 @@
        if ((sc->sc_read)(sc, 2, &spd_type) != 0)
                return 0;
 
+       /* Memory type should not be 0 */
+       if (spd_type == 0x00)
+               return 0;
+
        /* For older memory types, validate the checksum over 1st 63 bytes */
        if (spd_type <= SPDMEM_MEMTYPE_DDR2SDRAM) {
                for (i = 0; i < 63; i++) {
@@ -263,8 +267,7 @@
                 * it some other time.
                 */
                return 1;
-       } else
-               return 0;
+       }
 
        /* For unrecognized memory types, don't match at all */
        return 0;