[PATCH 8/9] powerpc/powernv: Discover and enable winkle

[Shreyas B. Prabhu]

Discover winkle from device tree. If supported make OPAL calls
necessary to save HIDs, HMEER, HSPRG0 and LPCR.
Also make OPAL call when the HID0 value is modified during
split/unsplit of cores.

Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Cc: Paul Mackerras <paulus at samba.org>
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: linuxppc-dev at lists.ozlabs.org
Signed-off-by: Shreyas B. Prabhu <shreyas at linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/opal.h          |  1 +
 arch/powerpc/platforms/powernv/powernv.h |  1 +
 arch/powerpc/platforms/powernv/setup.c   | 75 ++++++++++++++++++++++++++++++++
 arch/powerpc/platforms/powernv/subcore.c | 15 +++++++
 4 files changed, 92 insertions(+)

diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
index d376020..a77957f 100644
--- a/arch/powerpc/include/asm/opal.h
+++ b/arch/powerpc/include/asm/opal.h
@@ -778,6 +778,7 @@ extern struct device_node *opal_node;
 #define IDLE_INST_NAP	0x00010000 /* nap instruction can be used */
 #define IDLE_INST_SLEEP	0x00020000 /* sleep instruction can be used */
 #define IDLE_INST_SLEEP_ER1	0x00080000 /* Use sleep with work around*/
+#define IDLE_INST_WINKLE	0x00040000 /* winkle instruction can be used */
 
 /* API functions */
 int64_t opal_invalid_call(void);
diff --git a/arch/powerpc/platforms/powernv/powernv.h b/arch/powerpc/platforms/powernv/powernv.h
index 31ece13..76b37f8 100644
--- a/arch/powerpc/platforms/powernv/powernv.h
+++ b/arch/powerpc/platforms/powernv/powernv.h
@@ -27,6 +27,7 @@ static inline int pnv_pci_dma_set_mask(struct pci_dev *pdev, u64 dma_mask)
 
 #define IDLE_USE_NAP		(1UL << 0)
 #define IDLE_USE_SLEEP		(1UL << 1)
+#define IDLE_USE_WINKLE                (1UL << 3)
 
 extern unsigned int pnv_get_supported_cpuidle_states(void);
 
diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index f45b52d..13c5e49 100644
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -273,6 +273,65 @@ unsigned int pnv_get_supported_cpuidle_states(void)
 	return supported_cpuidle_states;
 }
 
+int pnv_save_sprs_for_winkle(void)
+{
+	int cpu;
+	int rc;
+
+	/*
+	* hid0, hid1, hid4, hid5, hmeer and lpcr values are symmetric accross
+	* all cpus at boot. Get these reg values of current cpu and use the
+	* same accross all cpus.
+	*/
+	uint64_t lpcr_val = mfspr(SPRN_LPCR);
+	uint64_t hid0_val = mfspr(SPRN_HID0);
+	uint64_t hid1_val = mfspr(SPRN_HID1);
+	uint64_t hid4_val = mfspr(SPRN_HID4);
+	uint64_t hid5_val = mfspr(SPRN_HID5);
+	uint64_t hmeer_val = mfspr(SPRN_HMEER);
+
+	for_each_possible_cpu(cpu) {
+		uint64_t pir = get_hard_smp_processor_id(cpu);
+		uint64_t local_paca_ptr = (uint64_t)&paca[cpu];
+
+		rc = opal_slw_set_reg(pir, SPRN_HSPRG0, local_paca_ptr);
+		if (rc != 0)
+			return rc;
+
+		rc = opal_slw_set_reg(pir, SPRN_LPCR, lpcr_val);
+		if (rc != 0)
+			return rc;
+
+		/* HIDs are per core registers */
+		if (cpu_thread_in_core(cpu) == 0) {
+
+			rc = opal_slw_set_reg(pir, SPRN_HMEER, hmeer_val);
+			if (rc != 0)
+				return rc;
+
+			rc = opal_slw_set_reg(pir, SPRN_HID0, hid0_val);
+			if (rc != 0)
+				return rc;
+
+			rc = opal_slw_set_reg(pir, SPRN_HID1, hid1_val);
+			if (rc != 0)
+				return rc;
+
+			rc = opal_slw_set_reg(pir, SPRN_HID4, hid4_val);
+			if (rc != 0)
+				return rc;
+
+			rc = opal_slw_set_reg(pir, SPRN_HID5, hid5_val);
+			if (rc != 0)
+				return rc;
+
+		}
+
+	}
+
+	return 0;
+
+}
 static int __init pnv_probe_idle_states(void)
 {
 	struct device_node *power_mgt;
@@ -318,6 +377,22 @@ static int __init pnv_probe_idle_states(void)
 			supported_cpuidle_states |= IDLE_USE_SLEEP;
 			need_fastsleep_workaround = 1;
 		}
+
+		if (flags & IDLE_INST_WINKLE) {
+			/*
+			 * If winkle is supported, save HSPRG0, HIDs and LPCR
+			 * contents via OPAL. Enable winkle only if this
+			 * succeeds.
+			 */
+			int opal_ret_val = pnv_save_sprs_for_winkle();
+
+			if (!opal_ret_val)
+				supported_cpuidle_states |= IDLE_USE_WINKLE;
+			else
+				pr_warn("opal: opal_slw_set_reg failed with rc=%d, disabling winkle\n",
+						opal_ret_val);
+		}
+
 	}
 
 	return 0;
diff --git a/arch/powerpc/platforms/powernv/subcore.c b/arch/powerpc/platforms/powernv/subcore.c
index 894ecb3..47c70666e 100644
--- a/arch/powerpc/platforms/powernv/subcore.c
+++ b/arch/powerpc/platforms/powernv/subcore.c
@@ -24,6 +24,7 @@
 #include <asm/smp.h>
 
 #include "subcore.h"
+#include "powernv.h"
 
 
 /*
@@ -159,6 +160,18 @@ static void wait_for_sync_step(int step)
 	mb();
 }
 
+static void update_hid_in_slw(u64 hid0)
+{
+	u64 idle_states = pnv_get_supported_cpuidle_states();
+
+	if (idle_states & IDLE_USE_WINKLE) {
+		/* OPAL call to patch slw with the new HID0 value */
+		u64 cpu_pir = hard_smp_processor_id();
+
+		opal_slw_set_reg(cpu_pir, SPRN_HID0, hid0);
+	}
+}
+
 static void unsplit_core(void)
 {
 	u64 hid0, mask;
@@ -178,6 +191,7 @@ static void unsplit_core(void)
 	hid0 = mfspr(SPRN_HID0);
 	hid0 &= ~HID0_POWER8_DYNLPARDIS;
 	mtspr(SPRN_HID0, hid0);
+	update_hid_in_slw(hid0);
 
 	while (mfspr(SPRN_HID0) & mask)
 		cpu_relax();
@@ -214,6 +228,7 @@ static void split_core(int new_mode)
 	hid0  = mfspr(SPRN_HID0);
 	hid0 |= HID0_POWER8_DYNLPARDIS | split_parms[i].value;
 	mtspr(SPRN_HID0, hid0);
+	update_hid_in_slw(hid0);
 
 	/* Wait for it to happen */
 	while (!(mfspr(SPRN_HID0) & split_parms[i].mask))
-- 
1.9.0