spmi: spmi-pmic-arb: add support for SPMI write corruption workaround
Add support for an AHB bus workaround which can be used to avoid
possible SPMI write transaction corruption on some platforms
which utilize PMIC arbiter version 5. The workaround consists
of performing dummy reads of a PMIC arbiter register reached
via the AHB bus immediately before each register write during
an SPMI write transaction.
Change-Id: I13c7535f9fe823f9a2e74263ee5d5b674e0c1fbc
Signed-off-by: David Collins <collinsd@codeaurora.org>
diff --git a/drivers/spmi/spmi-pmic-arb.c b/drivers/spmi/spmi-pmic-arb.c
index 7d9a2e8..b29e60d 100644
--- a/drivers/spmi/spmi-pmic-arb.c
+++ b/drivers/spmi/spmi-pmic-arb.c
@@ -59,6 +59,8 @@
#define SPMI_OWNERSHIP_TABLE_REG(N) (0x0700 + (4 * (N)))
#define SPMI_OWNERSHIP_PERIPH2OWNER(X) ((X) & 0x7)
+#define SPMI_PROTOCOL_IRQ_STATUS 0x6000
+
/* Channel Status fields */
enum pmic_arb_chnl_status {
PMIC_ARB_STATUS_DONE = BIT(0),
@@ -148,6 +150,8 @@
* @ver_ops: version dependent operations.
* @ppid_to_apid in-memory copy of PPID -> channel (APID) mapping table.
* v2 only.
+ * @ahb_bus_wa: Use AHB bus workaround to avoid write transaction
+ * corruption on some PMIC arbiter v5 platforms.
*/
struct spmi_pmic_arb {
void __iomem *rd_base;
@@ -172,6 +176,7 @@
u16 *ppid_to_apid;
u16 last_apid;
struct apid_data apid_data[PMIC_ARB_MAX_PERIPHS];
+ bool ahb_bus_wa;
};
/**
@@ -217,6 +222,16 @@
static inline void pmic_arb_base_write(struct spmi_pmic_arb *pa,
u32 offset, u32 val)
{
+ if (pa->ahb_bus_wa) {
+ /* AHB bus register dummy read for workaround. */
+ readl_relaxed(pa->cnfg + SPMI_PROTOCOL_IRQ_STATUS);
+ /*
+ * Ensure that the read completes before initiating the
+ * subsequent register write.
+ */
+ mb();
+ }
+
writel_relaxed(val, pa->wr_base + offset);
}
@@ -1343,6 +1358,9 @@
pa->ee = ee;
+ pa->ahb_bus_wa = of_property_read_bool(pdev->dev.of_node,
+ "qcom,enable-ahb-bus-workaround");
+
pa->mapping_table = devm_kcalloc(&ctrl->dev, PMIC_ARB_MAX_PERIPHS - 1,
sizeof(*pa->mapping_table), GFP_KERNEL);
if (!pa->mapping_table) {