[PATCH 04/21] amd64_edac: add memory scrubber interface

Borislav Petkov
2009-04-29T16:59:54Z

From: Doug Thompson <dougthompson@xmission.com>

Signed-off-by: Doug Thompson <dougthompson@xmission.com>
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
---
drivers/edac/amd64_edac.c | 116 +++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 116 insertions(+), 0 deletions(-)

diff --git a/drivers/edac/amd64_edac.c b/drivers/edac/amd64_edac.c
index 532a059..a121785 100644
--- a/drivers/edac/amd64_edac.c
+++ b/drivers/edac/amd64_edac.c
@@ -1000,3 +1000,119 @@ static struct scrubrate {
#define F10_MIN_SCRUB_RATE_BITS 0x5
#define F11_MIN_SCRUB_RATE_BITS 0x6

+/*
+ * Memory scrubber control interface. For the K8, memory scrubbing is handled by
+ * hardware and can involve L2 cache, dcache as well as the main memory. With
+ * F10, this is extended to L3 cache scrubbing on CPU models sporting that
+ * functionality.
+ * This causes the "units" for the scrubbing speed to vary from 64 byte blocks
+ * (dram) over to cache lines. This is nasty, so we will use bandwidth in
+ * bytes/sec for the setting.
+ * Currently, we only do dram scrubbing. If the scrubbing is done in software on
+ * other archs, we might not have access to the caches directly.
+ */
+
+/*
+ * amd64_search_set_scrub_rate
+ *
+ * scan the scrub rate mapping table for a close or matching bandwidth value to
+ * issue. If requested is too big, then use last maximum value found.
+ */
+static int amd64_search_set_scrub_rate(struct pci_dev *ctl, u32 new_bw,
+ u32 min_scrubrate)
+{
+ u32 scrubval;
+ int i;
+
+ /*
+ * map the configured rate (new_bw) to a value specific to the AMD64
+ * memory controller and apply to register. Search for the first
+ * bandwidth entry that is greater or equal than the setting requested
+ * and program that. If at last entry, accept that as the maximum. This
+ * saves the user from determing the maximum empirically.
+ */
+ for (i = 0; i < ARRAY_SIZE(scrubrates); i++) {
+ /*
+ * skip scrub rates which aren't recommended
+ * (see F10 BKDG, F3x58)
+ */
+ if (scrubrates[i].scrubval < min_scrubrate)
+ continue;
+
+ if (scrubrates[i].bandwidth <= new_bw)
+ break;
+
+ /*
+ * if no suitable bandwidth found, turn off DRAM scrubbing
+ * entirely by falling back to the last element in the
+ * scrubrates array.
+ */
+ }
+
+ scrubval = scrubrates[i].scrubval;
+ if (scrubval)
+ edac_printk(KERN_DEBUG, EDAC_MC,
+ "Setting scrub rate bandwidth: %u\n",
+ scrubrates[i].bandwidth);
+ else
+ edac_printk(KERN_DEBUG, EDAC_MC,
+ "Turning scrubbing off.\n");
+
+ pci_write_bits32(ctl, K8_SCRCTRL, scrubval, 0x001F);
+
+ return 0;
+}
+
+static int amd64_set_scrub_rate(struct mem_ctl_info *mci, u32 *bandwidth)
+{
+ struct amd64_pvt *pvt = mci->pvt_info;
+ u32 min_scrubrate = 0x0;
+
+ switch (boot_cpu_data.x86) {
+ case 0xf:
+ min_scrubrate = K8_MIN_SCRUB_RATE_BITS;
+ break;
+ case 0x10:
+ min_scrubrate = F10_MIN_SCRUB_RATE_BITS;
+ break;
+ case 0x11:
+ min_scrubrate = F11_MIN_SCRUB_RATE_BITS;
+ break;
+
+ default:
+ amd64_printk(KERN_ERR, "Unsupported family!\n");
+ break;
+ }
+ return amd64_search_set_scrub_rate(pvt->misc_f3_ctl, *bandwidth,
+ min_scrubrate);
+}
+
+static int amd64_get_scrub_rate(struct mem_ctl_info *mci, u32 *bw)
+{
+ struct amd64_pvt *pvt = mci->pvt_info;
+ u32 scrubval = 0;
+ int status = -1;
+ int i;
+ int err;
+
+ err = pci_read_config_dword(pvt->misc_f3_ctl, K8_SCRCTRL, &scrubval);
+ if (err != 0)
+ debugf0("%s() Reading K8_SCRCTRL failed\n", __func__);
+
+ scrubval = scrubval & 0x001F;
+
+ edac_printk(KERN_DEBUG, EDAC_MC,
+ "pci-read, sdram scrub control value: %d \n", scrubval);
+
+ for (i = 0; ARRAY_SIZE(scrubrates); i++) {
+ if (scrubrates[i].scrubval == scrubval) {
+ *bw = scrubrates[i].bandwidth;
+ status = 0;
+ break;
+ }
+ }
+
+ return status;
+}
+
+
--
1.6.2.4