[PATCH v10 7/8] clocksource/drivers/arm_arch_timer: Add GTDT support for memory-mapped timer

fu.wei
2016-07-26T12:21:47Z

From: Fu Wei <fu.wei@linaro.org>

The patch add memory-mapped timer register support by using the information
provided by the new GTDT driver of ACPI.

Signed-off-by: Fu Wei <fu.wei@linaro.org>
---
drivers/clocksource/arm_arch_timer.c | 127 ++++++++++++++++++++++++++++++++++-
1 file changed, 124 insertions(+), 3 deletions(-)

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index b10d84c..3f6a78c 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -870,7 +870,128 @@ CLOCKSOURCE_OF_DECLARE(armv7_arch_timer_mem, "arm,armv7-timer-mem",
arch_timer_mem_init);

#ifdef CONFIG_ACPI_GTDT
-/* Initialize per-processor generic timer */
+static struct gt_timer_data __init *arch_timer_mem_get_timer(
+ struct gt_block_data *gt_blocks)
+{
+ struct gt_block_data *gt_block = gt_blocks;
+ struct gt_timer_data *best_frame = NULL;
+ void __iomem *cntctlbase;
+ u32 cnttidr;
+ int i;
+
+ /*
+ * According to ARMv8 Architecture Reference Manual(ARM),
+ * the size of CNTCTLBase frame of memory-mapped timer
+ * is SZ_4K(Offset 0x000 – 0xFFF).
+ */
+ cntctlbase = ioremap(gt_block->cntctlbase_phy, SZ_4K);
+ if (!cntctlbase) {
+ pr_err("Failed to map mem timer control frame base address\n");
+ return NULL;
+ }
+ cnttidr = readl_relaxed(cntctlbase + CNTTIDR);
+
+ /*
+ * Try to find a virtual capable frame. Otherwise fall back to a
+ * physical capable frame.
+ */
+ for (i = 0; i < gt_block->timer_count; i++) {
+ int n;
+ u32 cntacr;
+
+ n = gt_block->timer[i].frame_nr;
+
+ /* Try enabling everything, and see what sticks */
+ cntacr = CNTACR_RFRQ | CNTACR_RWPT | CNTACR_RPCT |
+ CNTACR_RWVT | CNTACR_RVOFF | CNTACR_RVCT;
+ writel_relaxed(cntacr, cntctlbase + CNTACR(n));
+ cntacr = readl_relaxed(cntctlbase + CNTACR(n));
+
+ if ((cnttidr & CNTTIDR_VIRT(n)) &&
+ !(~cntacr & (CNTACR_RWVT | CNTACR_RVCT))) {
+ best_frame = &gt_block->timer[i];
+ arch_timer_mem_use_virtual = true;
+ break;
+ }
+
+ if (~cntacr & (CNTACR_RWPT | CNTACR_RPCT))
+ continue;
+
+ best_frame = &gt_block->timer[i];
+ }
+ iounmap(cntctlbase);
+
+ return best_frame;
+}
+
+static int __init arch_timer_mem_acpi_init(size_t timer_count)
+{
+ struct gt_block_data *gt_blocks;
+ struct gt_timer_data *gt_timer;
+ void __iomem *timer_cntbase;
+ int ret = -EINVAL;
+ int timer_irq;
+
+ /*
+ * If we don't have any Platform Timer Structures, just return.
+ */
+ if (!timer_count)
+ return 0;
+
+ /*
+ * before really check all the Platform Timer Structures,
+ * we assume they are GT block, and allocate memory for them.
+ * We will free these memory once we finish the initialization.
+ */
+ gt_blocks = kcalloc(timer_count, sizeof(*gt_blocks), GFP_KERNEL);
+ if (!gt_blocks)
+ return -ENOMEM;
+
+ if (gtdt_arch_timer_mem_init(gt_blocks) > 0) {
+ gt_timer = arch_timer_mem_get_timer(gt_blocks);
+ if (!gt_timer) {
+ pr_err("Failed to get mem timer info.\n");
+ goto error;
+ }
+
+ if (arch_timer_mem_use_virtual)
+ timer_irq = gt_timer->virtual_irq;
+ else
+ timer_irq = gt_timer->irq;
+ if (!timer_irq) {
+ pr_err("Failed to get %s irq for mem timer.",
+ arch_timer_mem_use_virtual ? "virt" : "phys");
+ goto error;
+ }
+
+ /*
+ * According to ARMv8 Architecture Reference Manual(ARM),
+ * the size of CNTBaseN frames of memory-mapped timer
+ * is SZ_4K(Offset 0x000 – 0xFFF).
+ */
+ timer_cntbase = ioremap(gt_timer->cntbase_phy, SZ_4K);
+ if (!timer_cntbase) {
+ pr_err("Failed to map mem timer base address.\n");
+ goto error;
+ }
+
+ ret = arch_timer_mem_register(timer_cntbase, timer_irq);
+ if (ret) {
+ iounmap(timer_cntbase);
+ pr_err("Failed to register mem timer.\n");
+ goto error;
+ }
+
+ arch_counter_base = timer_cntbase;
+ arch_timers_present |= ARCH_MEM_TIMER;
+ }
+
+error:
+ kfree(gt_blocks);
+ return ret;
+}
+
+/* Initialize per-processor generic timer and memory-mapped timer(if present) */
static int __init arch_timer_acpi_init(struct acpi_table_header *table)
{
int timer_count;
@@ -894,8 +1015,8 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table)
/* Get the frequency from CNTFRQ */
arch_timer_detect_rate(NULL, NULL);

- if (timer_count < 0)
- pr_err("Failed to get platform timer info, skipping.\n");
+ if (timer_count < 0 || arch_timer_mem_acpi_init((size_t)timer_count))
+ pr_err("Failed to initialize memory-mapped timer, skipping.\n");

return arch_timer_init();
}
--
2.5.5

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