[PATCH v2] lib: utils/mtimer: Add has_broken_mtime quirk

[Anup Patel]

The Allwinner D1 SoC has custom CLINT implementation where the
MTIME register of the timer is not accessible as MMIO register
instead the time CSR is to be used as MTIME.

We introduce "has_broken_mtime" quirk in MTIMER library and FDT
based MTIMER driver to address the Allwiner D1 situation. And
while we are here, let us extend the quirk mechanism in FDT based
MTIMER driver for both CLINT and ACLINT.

Signed-off-by: Anup Patel <apatel at ventanamicro.com>
---
Changes since v1:
 - Rebased on latest OpenSBI
 - Removed mtimer_dummy_value() from aclint_mtimer.c
---
 include/sbi_utils/timer/aclint_mtimer.h |  1 +
 lib/utils/timer/aclint_mtimer.c         | 24 +++++++++++++++-------
 lib/utils/timer/fdt_timer_mtimer.c      | 27 ++++++++++++++++++-------
 3 files changed, 38 insertions(+), 14 deletions(-)

diff --git a/include/sbi_utils/timer/aclint_mtimer.h b/include/sbi_utils/timer/aclint_mtimer.h
index f02cc62..454a92f 100644
--- a/include/sbi_utils/timer/aclint_mtimer.h
+++ b/include/sbi_utils/timer/aclint_mtimer.h
@@ -32,6 +32,7 @@ struct aclint_mtimer_data {
 	u32 first_hartid;
 	u32 hart_count;
 	bool has_64bit_mmio;
+	bool has_broken_mtime;
 	bool has_shared_mtime;
 	/* Private details (initialized and used by ACLINT MTIMER library) */
 	struct aclint_mtimer_data *time_delta_reference;
diff --git a/lib/utils/timer/aclint_mtimer.c b/lib/utils/timer/aclint_mtimer.c
index a957b1c..cf492d1 100644
--- a/lib/utils/timer/aclint_mtimer.c
+++ b/lib/utils/timer/aclint_mtimer.c
@@ -95,7 +95,9 @@ void aclint_mtimer_sync(struct aclint_mtimer_data *mt)
 	struct aclint_mtimer_data *reference;
 
 	/* Sync-up non-shared MTIME if reference is available */
-	if (mt->has_shared_mtime || !mt->time_delta_reference)
+	if (mt->has_broken_mtime ||
+	    mt->has_shared_mtime ||
+	    !mt->time_delta_reference)
 		return;
 
 	reference = mt->time_delta_reference;
@@ -189,6 +191,10 @@ int aclint_mtimer_cold_init(struct aclint_mtimer_data *mt,
 	if (reference && mt->mtime_freq != reference->mtime_freq)
 		return SBI_EINVAL;
 
+	/* Set timer_value() callback to NULL for broken MTIME */
+	if (mt->has_broken_mtime)
+		mtimer.timer_value = NULL;
+
 	/* Initialize private data */
 	aclint_mtimer_set_reference(mt, reference);
 	mt->time_rd = mtimer_time_rd32;
@@ -207,21 +213,25 @@ int aclint_mtimer_cold_init(struct aclint_mtimer_data *mt,
 		mtimer_hartid2data[mt->first_hartid + i] = mt;
 
 	/* Add MTIMER regions to the root domain */
-	if (mt->mtime_addr == (mt->mtimecmp_addr + mt->mtimecmp_size)) {
+	if (!mt->has_broken_mtime &&
+	    mt->mtime_addr == (mt->mtimecmp_addr + mt->mtimecmp_size)) {
 		rc = aclint_mtimer_add_regions(mt->mtimecmp_addr,
 					mt->mtime_size + mt->mtimecmp_size);
 		if (rc)
 			return rc;
-	} else if (mt->mtimecmp_addr == (mt->mtime_addr + mt->mtime_size)) {
+	} else if (!mt->has_broken_mtime &&
+		   mt->mtimecmp_addr == (mt->mtime_addr + mt->mtime_size)) {
 		rc = aclint_mtimer_add_regions(mt->mtime_addr,
 					mt->mtime_size + mt->mtimecmp_size);
 		if (rc)
 			return rc;
 	} else {
-		rc = aclint_mtimer_add_regions(mt->mtime_addr,
-						mt->mtime_size);
-		if (rc)
-			return rc;
+		if (!mt->has_broken_mtime) {
+			rc = aclint_mtimer_add_regions(mt->mtime_addr,
+							mt->mtime_size);
+			if (rc)
+				return rc;
+		}
 
 		rc = aclint_mtimer_add_regions(mt->mtimecmp_addr,
 						mt->mtimecmp_size);
diff --git a/lib/utils/timer/fdt_timer_mtimer.c b/lib/utils/timer/fdt_timer_mtimer.c
index 7b8546b..41fe0a0 100644
--- a/lib/utils/timer/fdt_timer_mtimer.c
+++ b/lib/utils/timer/fdt_timer_mtimer.c
@@ -16,8 +16,10 @@
 #define MTIMER_MAX_NR			16
 
 struct timer_mtimer_quirks {
+	bool		is_clint;
 	unsigned int	mtime_offset;
 	bool		has_64bit_mmio;
+	bool		has_broken_mtime;
 };
 
 static unsigned long mtimer_count = 0;
@@ -30,6 +32,11 @@ static int timer_mtimer_cold_init(void *fdt, int nodeoff,
 	int i, rc;
 	unsigned long addr[2], size[2];
 	struct aclint_mtimer_data *mt;
+	const struct timer_mtimer_quirks *quirks;
+
+	if (!match->data)
+		return SBI_ENOSYS;
+	quirks = match->data;
 
 	if (MTIMER_MAX_NR <= mtimer_count)
 		return SBI_ENOSPC;
@@ -40,16 +47,15 @@ static int timer_mtimer_cold_init(void *fdt, int nodeoff,
 				   &mt->first_hartid, &mt->hart_count);
 	if (rc)
 		return rc;
-	mt->has_64bit_mmio = true;
+	mt->has_64bit_mmio = quirks->has_64bit_mmio;
 	mt->has_shared_mtime = false;
+	mt->has_broken_mtime = quirks->has_broken_mtime;
 
 	rc = fdt_parse_timebase_frequency(fdt, &mt->mtime_freq);
 	if (rc)
 		return rc;
 
-	if (match->data) { /* SiFive CLINT */
-		const struct timer_mtimer_quirks *quirks = match->data;
-
+	if (quirks->is_clint) { /* SiFive CLINT */
 		/* Set CLINT addresses */
 		mt->mtimecmp_addr = addr[0] + ACLINT_DEFAULT_MTIMECMP_OFFSET;
 		mt->mtimecmp_size = ACLINT_DEFAULT_MTIMECMP_SIZE;
@@ -59,8 +65,6 @@ static int timer_mtimer_cold_init(void *fdt, int nodeoff,
 		mt->mtime_addr += quirks->mtime_offset;
 		mt->mtimecmp_addr += quirks->mtime_offset;
 		mt->mtime_size -= quirks->mtime_offset;
-		/* Apply additional CLINT quirks */
-		mt->has_64bit_mmio = quirks->has_64bit_mmio;
 	} else { /* RISC-V ACLINT MTIMER */
 		/* Set ACLINT MTIMER addresses */
 		mt->mtime_addr = addr[0];
@@ -110,14 +114,23 @@ static int timer_mtimer_cold_init(void *fdt, int nodeoff,
 }
 
 static const struct timer_mtimer_quirks sifive_clint_quirks = {
+	.is_clint	= true,
 	.mtime_offset	= CLINT_MTIMER_OFFSET,
 	.has_64bit_mmio	= true,
+	.has_broken_mtime = false,
+};
+
+static const struct timer_mtimer_quirks aclint_quirks = {
+	.is_clint	= false,
+	.mtime_offset	= 0,
+	.has_64bit_mmio	= true,
+	.has_broken_mtime = false,
 };
 
 static const struct fdt_match timer_mtimer_match[] = {
 	{ .compatible = "riscv,clint0", .data = &sifive_clint_quirks },
 	{ .compatible = "sifive,clint0", .data = &sifive_clint_quirks },
-	{ .compatible = "riscv,aclint-mtimer" },
+	{ .compatible = "riscv,aclint-mtimer", .data = &aclint_quirks },
 	{ },
 };
 
-- 
2.34.1