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diff --git a/sys/dev/jedec_dimm/jedec_dimm.c b/sys/dev/jedec_dimm/jedec_dimm.c
--- a/sys/dev/jedec_dimm/jedec_dimm.c
+++ b/sys/dev/jedec_dimm/jedec_dimm.c
@@ -144,6 +144,9 @@
{ 0x104a, 0x03, "ST Microelectronics TSOD" },
};
+static int jedec_dimm_adjust_offset(struct jedec_dimm_softc *sc,
+ uint16_t orig_offset, uint16_t *new_offset, bool *page_changed);
+
static int jedec_dimm_attach(device_t dev);
static int jedec_dimm_capacity(struct jedec_dimm_softc *sc, enum dram_type type,
@@ -164,11 +167,81 @@
static int jedec_dimm_readw_be(struct jedec_dimm_softc *sc, uint8_t reg,
uint16_t *val);
+static int jedec_dimm_reset_page0(struct jedec_dimm_softc *sc);
+
static int jedec_dimm_temp_sysctl(SYSCTL_HANDLER_ARGS);
static const char *jedec_dimm_tsod_match(uint16_t vid, uint16_t did);
+/**
+ * The DDR4 SPD information is spread across two 256-byte pages, but the
+ * offsets in the spec are absolute, not per-page. If a given offset is on the
+ * second page, we need to change to that page and adjust the offset to be
+ * relative to that page.
+ *
+ * @author rpokala
+ *
+ * @param[in] sc
+ * Instance-specific context data
+ *
+ * @param[in] orig_offset
+ * The original value of the offset, before any adjustment is made.
+ *
+ * @param[out] new_offset
+ * The offset to actually read from, adjusted if needed.
+ *
+ * @param[out] page_changed
+ * Whether or not the page was actually changed, and the offset adjusted.
+ * *If 'true', caller must call reset_page0() before itself returning.*
+ */
+static int
+jedec_dimm_adjust_offset(struct jedec_dimm_softc *sc, uint16_t orig_offset,
+ uint16_t *new_offset, bool *page_changed)
+{
+ int rc;
+
+ /* Don't change the offset, or indicate that the page has been changed,
+ * until the page has actually been changed.
+ */
+ *new_offset = orig_offset;
+ *page_changed = false;
+
+ /* Change to the proper page. Offsets [0, 255] are in page0; offsets
+ * [256, 511] are in page1.
+ */
+ if (orig_offset < JEDEC_SPD_PAGE_SIZE) {
+ /* Within page0; no adjustment or page-change required. */
+ rc = 0;
+ goto out;
+ } else if (orig_offset >= (2 * JEDEC_SPD_PAGE_SIZE)) {
+ /* Outside of expected range. */
+ rc = EINVAL;
+ device_printf(sc->dev, "invalid offset 0x%04x\n", orig_offset);
+ goto out;
+ }
+
+ /* 'orig_offset' is in page1. Switch to that page, and adjust
+ * 'new_offset' accordingly if successful.
+ *
+ * For the page-change operation, only the DTI and LSA matter; the
+ * offset and write-value are ignored, so just use 0.
+ */
+ rc = smbus_writeb(sc->smbus, (JEDEC_DTI_PAGE | JEDEC_LSA_PAGE_SET1),
+ 0, 0);
+ if (rc != 0) {
+ device_printf(sc->dev,
+ "unable to change page for offset 0x%04x: %d\n",
+ orig_offset, rc);
+ goto out;
+ }
+ *page_changed = true;
+ *new_offset = orig_offset - JEDEC_SPD_PAGE_SIZE;
+
+out:
+ return (rc);
+}
+
/**
* device_attach() method. Read the DRAM type, use that to determine the offsets
* and lengths of the asset string fields. Calculate the capacity. If a TSOD is
@@ -458,9 +531,7 @@
sdram_width_offset = SPD_OFFSET_DDR4_SDRAM_WIDTH;
break;
default:
- device_printf(sc->dev, "unsupported dram_type 0x%02x\n", type);
- rc = EINVAL;
- goto out;
+ __assert_unreachable();
}
rc = smbus_readb(sc->smbus, sc->spd_addr, bus_width_offset,
@@ -673,14 +744,13 @@
out:
if (page_changed) {
int rc2;
- /* Switch back to page0 before returning. */
- rc2 = smbus_writeb(sc->smbus,
- (JEDEC_DTI_PAGE | JEDEC_LSA_PAGE_SET0), 0, 0);
- if (rc2 != 0) {
- device_printf(sc->dev, "unable to restore page: %d\n",
- rc2);
+
+ rc2 = jedec_dimm_reset_page0(sc);
+ if ((rc2 != 0) && (rc == 0)) {
+ rc = rc2;
}
}
+
return (rc);
}
@@ -715,54 +785,29 @@
uint16_t offset, uint16_t len, bool ascii)
{
uint8_t byte;
+ uint16_t new_offset;
int i;
int rc;
bool page_changed;
- /* Change to the proper page. Offsets [0, 255] are in page0; offsets
- * [256, 512] are in page1.
- *
- * *The page must be reset to page0 before returning.*
- *
- * For the page-change operation, only the DTI and LSA matter; the
- * offset and write-value are ignored, so use just 0.
- *
- * Mercifully, JEDEC defined the fields such that none of them cross
- * pages, so we don't need to worry about that complication.
- */
- if (offset < JEDEC_SPD_PAGE_SIZE) {
- page_changed = false;
- } else if (offset < (2 * JEDEC_SPD_PAGE_SIZE)) {
- page_changed = true;
- rc = smbus_writeb(sc->smbus,
- (JEDEC_DTI_PAGE | JEDEC_LSA_PAGE_SET1), 0, 0);
- if (rc != 0) {
- device_printf(sc->dev,
- "unable to change page for offset 0x%04x: %d\n",
- offset, rc);
- }
- /* Adjust the offset to account for the page change. */
- offset -= JEDEC_SPD_PAGE_SIZE;
- } else {
- page_changed = false;
- rc = EINVAL;
- device_printf(sc->dev, "invalid offset 0x%04x\n", offset);
+ rc = jedec_dimm_adjust_offset(sc, offset, &new_offset, &page_changed);
+ if (rc != 0) {
goto out;
}
/* Sanity-check (adjusted) offset and length; everything must be within
* the same page.
*/
- if (offset >= JEDEC_SPD_PAGE_SIZE) {
+ if (new_offset >= JEDEC_SPD_PAGE_SIZE) {
rc = EINVAL;
- device_printf(sc->dev, "invalid offset 0x%04x\n", offset);
+ device_printf(sc->dev, "invalid offset 0x%04x\n", new_offset);
goto out;
}
- if ((offset + len) >= JEDEC_SPD_PAGE_SIZE) {
+ if ((new_offset + len) >= JEDEC_SPD_PAGE_SIZE) {
rc = EINVAL;
device_printf(sc->dev,
- "(offset + len) would cross page (0x%04x + 0x%04x)\n",
- offset, len);
+ "(new_offset + len) would cross page (0x%04x + 0x%04x)\n",
+ new_offset, len);
goto out;
}
@@ -793,11 +838,12 @@
/* Read a byte at a time. */
for (i = 0; i < len; i++) {
- rc = smbus_readb(sc->smbus, sc->spd_addr, (offset + i), &byte);
+ rc = smbus_readb(sc->smbus, sc->spd_addr, (new_offset + i),
+ &byte);
if (rc != 0) {
device_printf(sc->dev,
"failed to read byte at 0x%02x: %d\n",
- (offset + i), rc);
+ (new_offset + i), rc);
goto out;
}
if (ascii) {
@@ -827,13 +873,10 @@
out:
if (page_changed) {
int rc2;
- /* Switch back to page0 before returning. */
- rc2 = smbus_writeb(sc->smbus,
- (JEDEC_DTI_PAGE | JEDEC_LSA_PAGE_SET0), 0, 0);
- if (rc2 != 0) {
- device_printf(sc->dev,
- "unable to restore page for offset 0x%04x: %d\n",
- offset, rc2);
+
+ rc2 = jedec_dimm_reset_page0(sc);
+ if ((rc2 != 0) && (rc == 0)) {
+ rc = rc2;
}
}
@@ -880,10 +923,7 @@
week_offset = SPD_OFFSET_DDR4_MOD_MFG_WEEK;
break;
default:
- device_printf(sc->dev, "unsupported dram_type 0x%02x\n", type);
- rc = EINVAL;
- page_changed = false;
- goto out;
+ __assert_unreachable();
}
/* Change to the proper page. Offsets [0, 255] are in page0; offsets
@@ -1041,6 +1081,32 @@
return (rc);
}
+/**
+ * Reset to the default condition of operating on page0. This must be called
+ * after a previous operation changed to page1.
+ *
+ * @author rpokala
+ *
+ * @param[in] sc
+ * Instance-specific context data
+ */
+static int
+jedec_dimm_reset_page0(struct jedec_dimm_softc *sc)
+{
+ int rc;
+
+ /* For the page-change operation, only the DTI and LSA matter; the
+ * offset and write-value are ignored, so just use 0.
+ */
+ rc = smbus_writeb(sc->smbus, (JEDEC_DTI_PAGE | JEDEC_LSA_PAGE_SET0),
+ 0, 0);
+ if (rc != 0) {
+ device_printf(sc->dev, "unable to restore page: %d\n", rc);
+ }
+
+ return (rc);
+}
+
/**
* Read the temperature data from the TSOD and convert it to the deciKelvin
* value that the sysctl expects.

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