arm: Add PL031 test

This patch adds a unit test for the PL031 RTC that is used in the virt machine. It just pokes basic functionality. I've mostly written it to familiarize myself with the device, but I suppose having the test around does not hurt, as it also exercises the GIC SPI interrupt path.

Signed-off-by Alexander Graf <[email protected]>

---

v1 -> v2:

- Use FDT to find base, irq and existence
- Put isb after timer read
- Use dist_base for gicv3

---
 arm/Makefile.common |   1 +
 arm/pl031.c         | 265 ++++++++++++++++++++++++++++++++++++++++++++
 lib/arm/asm/gic.h   |   1 +
 3 files changed, 267 insertions(+)
 create mode 100644 arm/pl031.c

arm/Makefile.common +0 -0

index f0c4b5d..b8988f2 100644

arm/Makefile.common +0 -0

 tests-all = $(tests-common) $(tests)
 all: directories $(tests-all)

arm/pl031.c new file +229 -0

new file mode 100644
index 0000000..d975937
@@ -0,0 +1,265 @@
+/*
+ * Verify PL031 functionality
+ *
+ * This test verifies whether the emulated PL031 behaves correctly.
+ *
+ * Copyright 2019 Amazon.com, Inc. or its affiliates.
+ * Author: Alexander Graf <[email protected]>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.
+ */
+#include <libcflat.h>
+#include <devicetree.h>
+#include <asm/processor.h>
+#include <asm/io.h>
+#include <asm/gic.h>
+
+struct pl031_regs {
+	uint32_t dr;	/* Data Register */
+	uint32_t mr;	/* Match Register */
+	uint32_t lr;	/* Load Register */
+	union {
+		uint8_t cr;	/* Control Register */
+		uint32_t cr32;
+	};
+	union {
+		uint8_t imsc;	/* Interrupt Mask Set or Clear register */
+		uint32_t imsc32;
+	};
+	union {
+		uint8_t ris;	/* Raw Interrupt Status */
+		uint32_t ris32;
+	};
+	union {
+		uint8_t mis;	/* Masked Interrupt Status */
+		uint32_t mis32;
+	};
+	union {
+		uint8_t icr;	/* Interrupt Clear Register */
+		uint32_t icr32;
+	};
+	uint32_t reserved[1008];
+	uint32_t periph_id[4];
+	uint32_t pcell_id[4];
+};
+
+static u32 cntfrq;
+static struct pl031_regs *pl031;
+static int pl031_irq;
+static void *gic_ispendr;
+static void *gic_isenabler;
+static bool irq_triggered;
+
+static uint64_t read_timer(void)
+{
+	uint64_t r = read_sysreg(cntpct_el0);
+	isb();
+
+	return r;
+}
+
+static int check_id(void)
+{
+	uint32_t id[] = { 0x31, 0x10, 0x14, 0x00, 0x0d, 0xf0, 0x05, 0xb1 };
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(id); i++)
+		if (id[i] != readl(&pl031->periph_id[i]))
+			return 1;
+
+	return 0;
+}
+
+static int check_ro(void)
+{
+	uint32_t offs[] = { offsetof(struct pl031_regs, ris),
+			    offsetof(struct pl031_regs, mis),
+			    offsetof(struct pl031_regs, periph_id[0]),
+			    offsetof(struct pl031_regs, periph_id[1]),
+			    offsetof(struct pl031_regs, periph_id[2]),
+			    offsetof(struct pl031_regs, periph_id[3]),
+			    offsetof(struct pl031_regs, pcell_id[0]),
+			    offsetof(struct pl031_regs, pcell_id[1]),
+			    offsetof(struct pl031_regs, pcell_id[2]),
+			    offsetof(struct pl031_regs, pcell_id[3]) };
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(offs); i++) {
+		uint32_t before32;
+		uint16_t before16;
+		uint8_t before8;
+		void *addr = (void*)pl031 + offs[i];
+		uint32_t poison = 0xdeadbeefULL;
+
+		before8 = readb(addr);
+		before16 = readw(addr);
+		before32 = readl(addr);
+
+		writeb(poison, addr);
+		writew(poison, addr);
+		writel(poison, addr);
+
+		if (before8 != readb(addr))
+			return 1;
+		if (before16 != readw(addr))
+			return 1;
+		if (before32 != readl(addr))
+			return 1;
+	}
+
+	return 0;
+}
+
+static int check_rtc_freq(void)
+{
+	uint32_t seconds_to_wait = 2;
+	uint32_t before = readl(&pl031->dr);
+	uint64_t before_tick = read_timer();
+	uint64_t target_tick = before_tick + (cntfrq * seconds_to_wait);
+
+	/* Wait for 2 seconds */
+	while (read_timer() < target_tick) ;
+
+	if (readl(&pl031->dr) != before + seconds_to_wait)
+		return 1;
+
+	return 0;
+}
+
+static bool gic_irq_pending(void)
+{
+	uint32_t offset = (pl031_irq / 32) * 4;
+
+	return readl(gic_ispendr + offset) & (1 << (pl031_irq & 31));
+}
+
+static void gic_irq_unmask(void)
+{
+	uint32_t offset = (pl031_irq / 32) * 4;
+
+	writel(1 << (pl031_irq & 31), gic_isenabler + offset);
+}
+
+static void irq_handler(struct pt_regs *regs)
+{
+	u32 irqstat = gic_read_iar();
+	u32 irqnr = gic_iar_irqnr(irqstat);
+
+	gic_write_eoir(irqstat);
+
+	if (irqnr == pl031_irq) {
+		report("  RTC RIS == 1", readl(&pl031->ris) == 1);
+		report("  RTC MIS == 1", readl(&pl031->mis) == 1);
+
+		/* Writing any value should clear IRQ status */
+		writel(0x80000000ULL, &pl031->icr);
+
+		report("  RTC RIS == 0", readl(&pl031->ris) == 0);
+		report("  RTC MIS == 0", readl(&pl031->mis) == 0);
+		irq_triggered = true;
+	} else {
+		report_info("Unexpected interrupt: %d\n", irqnr);
+		return;
+	}
+}
+
+static int check_rtc_irq(void)
+{
+	uint32_t seconds_to_wait = 1;
+	uint32_t before = readl(&pl031->dr);
+	uint64_t before_tick = read_timer();
+	uint64_t target_tick = before_tick + (cntfrq * (seconds_to_wait + 1));
+
+	report_info("Checking IRQ trigger (MR)");
+
+	irq_triggered = false;
+
+	/* Fire IRQ in 1 second */
+	writel(before + seconds_to_wait, &pl031->mr);
+
+	install_irq_handler(EL1H_IRQ, irq_handler);
+
+	/* Wait until 2 seconds are over */
+	while (read_timer() < target_tick) ;
+
+	report("  RTC IRQ not delivered without mask", !gic_irq_pending());
+
+	/* Mask the IRQ so that it gets delivered */
+	writel(1, &pl031->imsc);
+	report("  RTC IRQ pending now", gic_irq_pending());
+
+	/* Enable retrieval of IRQ */
+	gic_irq_unmask();
+	local_irq_enable();
+
+	report("  IRQ triggered", irq_triggered);
+	report("  RTC IRQ not pending anymore", !gic_irq_pending());
+	if (!irq_triggered) {
+		report_info("  RTC RIS: %x", readl(&pl031->ris));
+		report_info("  RTC MIS: %x", readl(&pl031->mis));
+		report_info("  RTC IMSC: %x", readl(&pl031->imsc));
+		report_info("  GIC IRQs pending: %08x %08x", readl(gic_ispendr), readl(gic_ispendr + 4));
+	}
+
+	local_irq_disable();
+	return 0;
+}
+
+static void rtc_irq_init(void)
+{
+	gic_enable_defaults();
+
+	switch (gic_version()) {
+	case 2:
+		gic_ispendr = gicv2_dist_base() + GICD_ISPENDR;
+		gic_isenabler = gicv2_dist_base() + GICD_ISENABLER;
+		break;
+	case 3:
+		gic_ispendr = gicv3_dist_base() + GICD_ISPENDR;
+		gic_isenabler = gicv3_dist_base() + GICD_ISENABLER;
+		break;
+	}
+}
+
+static int rtc_fdt_init(void)
+{
+	const struct fdt_property *prop;
+	const void *fdt = dt_fdt();
+	int node, len;
+	u32 *data;

arm/pl031.c new file +21 -0

+
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	cntfrq = get_cntfrq();
+	rtc_irq_init();
+	if (rtc_fdt_init()) {
+		report_skip("Skipping PL031 tests. No device present.");
+		return 0;
+	}
+
+	report("Periph/PCell IDs match", !check_id());
+	report("R/O fields are R/O", !check_ro());
+	report("RTC ticks at 1HZ", !check_rtc_freq());
+	report("RTC IRQ not pending yet", !gic_irq_pending());
+	check_rtc_irq();
+
+	return report_summary();
+}

lib/arm/asm/gic.h +1 -0

index f6dfb90..1fc10a0 100644
@@ -41,6 +41,7 @@
 #include <asm/gic-v3.h>
 
 #define PPI(irq)			((irq) + 16)
+#define SPI(irq)			((irq) + GIC_FIRST_SPI)
 
 #ifndef __ASSEMBLY__
 #include <asm/cpumask.h>

Signature · 1 line

2.17.1

Quoted 21 lines · Alexander Graf

This patch adds a unit test for the PL031 RTC that is used in the virt machine. It just pokes basic functionality. I've mostly written it to familiarize myself with the device, but I suppose having the test around does not hurt, as it also exercises the GIC SPI interrupt path.

Signed-off-by Alexander Graf <[email protected]>

---

v1 -> v2:

- Use FDT to find base, irq and existence
- Put isb after timer read
- Use dist_base for gicv3

---
  arm/Makefile.common |   1 +
  arm/pl031.c         | 265 ++++++++++++++++++++++++++++++++++++++++++++
  lib/arm/asm/gic.h   |   1 +
  3 files changed, 267 insertions(+)

create mode 100644 arm/pl031.c

arm/Makefile.common tests-common += $(TEST_DIR)/pmu.flat · line 14

Quoted 9 lines

arm/Makefile.common +1 -0

index f0c4b5d..b8988f2 100644
@@ -11,6 +11,7 @@ tests-common += $(TEST_DIR)/pmu.flat
  tests-common += $(TEST_DIR)/gic.flat
  tests-common += $(TEST_DIR)/psci.flat
  tests-common += $(TEST_DIR)/sieve.flat
+tests-common += $(TEST_DIR)/pl031.flat

Makefile.common is for both arm32 and arm64, but this code is only compilable on arm64. As there's no reason for it to be arm64 only, then ideally we'd modify the code to allow compiling and running on both, but otherwise we need to move this to Makefile.arm64.

Quoted 12 lines

arm/Makefile.common +12 -0

+static int rtc_fdt_init(void)
+{
+	const struct fdt_property *prop;
+	const void *fdt = dt_fdt();
+	int node, len;
+	u32 *data;
+
+	node = fdt_node_offset_by_compatible(fdt, -1, "arm,pl031");
+	if (node < 0)
+		return -1;
+
+	prop = fdt_get_property(fdt, node, "interrupts", &len);

arm/Makefile.common

Quoted 4 lines

arm/Makefile.common +4 -0

+	assert(prop && len == (3 * sizeof(u32)));
+	data = (u32 *)prop->data;
+	assert(data[0] == 0); /* SPI */
+	pl031_irq = SPI(fdt32_to_cpu(data[1]));

Nit: Ideally we'd add some more devicetree API to get interrupts. With that, and the existing devicetree API, we could remove all low-level fdt related code in this function.

arm/Makefile.common

Quoted 6 lines

arm/Makefile.common +5 -0

+
+	prop = fdt_get_property(fdt, node, "reg", &len);
+	assert(prop && len == (2 * sizeof(u64)));
+	data = (u32 *)prop->data;
+	pl031 = (void*)((ulong)fdt32_to_cpu(data[0]) << 32 | fdt32_to_cpu(data[1]));

This works because we currently ID map all the physical memory. I usually try to remember to use an ioremap in these cases anyway though.

Quoted 22 lines · Andrew Jones

Quoted 21 lines · Alexander Graf

This patch adds a unit test for the PL031 RTC that is used in the virt machine. It just pokes basic functionality. I've mostly written it to familiarize myself with the device, but I suppose having the test around does not hurt, as it also exercises the GIC SPI interrupt path.

Signed-off-by Alexander Graf <[email protected]>

---

v1 -> v2:

- Use FDT to find base, irq and existence
- Put isb after timer read
- Use dist_base for gicv3

---
  arm/Makefile.common |   1 +
  arm/pl031.c         | 265 ++++++++++++++++++++++++++++++++++++++++++++
  lib/arm/asm/gic.h   |   1 +
  3 files changed, 267 insertions(+)

create mode 100644 arm/pl031.c

Quoted 14 lines

arm/Makefile.common tests-common += $(TEST_DIR)/pmu.flat · line 14

Quoted 9 lines

arm/Makefile.common +1 -0

index f0c4b5d..b8988f2 100644
@@ -11,6 +11,7 @@ tests-common += $(TEST_DIR)/pmu.flat
  tests-common += $(TEST_DIR)/gic.flat
  tests-common += $(TEST_DIR)/psci.flat
  tests-common += $(TEST_DIR)/sieve.flat
+tests-common += $(TEST_DIR)/pl031.flat

Makefile.common is for both arm32 and arm64, but this code is only compilable on arm64. As there's no reason for it to be arm64 only, then ideally we'd modify the code to allow compiling and running on both, but otherwise we need to move this to Makefile.arm64.

D'oh. Sorry, I completely missed that bit. Of course we want to test on 32bit ARM as well! I'll fix it up :).

[...]

Quoted 12 lines

Quoted 12 lines

arm/Makefile.common +12 -0

+static int rtc_fdt_init(void)
+{
+	const struct fdt_property *prop;
+	const void *fdt = dt_fdt();
+	int node, len;
+	u32 *data;
+
+	node = fdt_node_offset_by_compatible(fdt, -1, "arm,pl031");
+	if (node < 0)
+		return -1;
+
+	prop = fdt_get_property(fdt, node, "interrupts", &len);

Quoted 8 lines

arm/Makefile.common

Quoted 4 lines

arm/Makefile.common +4 -0

+	assert(prop && len == (3 * sizeof(u32)));
+	data = (u32 *)prop->data;
+	assert(data[0] == 0); /* SPI */
+	pl031_irq = SPI(fdt32_to_cpu(data[1]));

Nit: Ideally we'd add some more devicetree API to get interrupts. With that, and the existing devicetree API, we could remove all low-level fdt related code in this function.

Well, we probably want some really high level fdt API that can traverse reg properly to map bus regs into physical addresses. As long as we don't have all that magic,

I see little point in inventing anything that looks more sophisticated but doesn't actually take the difficult problems into account :).

Quoted 10 lines

arm/Makefile.common

Quoted 7 lines

arm/Makefile.common +5 -0

+
+	prop = fdt_get_property(fdt, node, "reg", &len);
+	assert(prop && len == (2 * sizeof(u64)));
+	data = (u32 *)prop->data;
+	pl031 = (void*)((ulong)fdt32_to_cpu(data[0]) << 32 | fdt32_to_cpu(data[1]));

This works because we currently ID map all the physical memory. I usually try to remember to use an ioremap in these cases anyway though.

Great idea - it allows me to get rid of a bit of casting too.

Quoted 67 lines · Alexander Graf

Quoted 22 lines · Andrew Jones

Quoted 21 lines · Alexander Graf

This patch adds a unit test for the PL031 RTC that is used in the virt machine. It just pokes basic functionality. I've mostly written it to familiarize myself with the device, but I suppose having the test around does not hurt, as it also exercises the GIC SPI interrupt path.

Signed-off-by Alexander Graf <[email protected]>

---

v1 -> v2:

- Use FDT to find base, irq and existence
- Put isb after timer read
- Use dist_base for gicv3

---
   arm/Makefile.common |   1 +
   arm/pl031.c         | 265 ++++++++++++++++++++++++++++++++++++++++++++
   lib/arm/asm/gic.h   |   1 +
   3 files changed, 267 insertions(+)

create mode 100644 arm/pl031.c

Quoted 14 lines

arm/Makefile.common tests-common += $(TEST_DIR)/pmu.flat · line 14

Quoted 9 lines

arm/Makefile.common +1 -0

index f0c4b5d..b8988f2 100644
@@ -11,6 +11,7 @@ tests-common += $(TEST_DIR)/pmu.flat
   tests-common += $(TEST_DIR)/gic.flat
   tests-common += $(TEST_DIR)/psci.flat
   tests-common += $(TEST_DIR)/sieve.flat
+tests-common += $(TEST_DIR)/pl031.flat

Makefile.common is for both arm32 and arm64, but this code is only compilable on arm64. As there's no reason for it to be arm64 only, then ideally we'd modify the code to allow compiling and running on both, but otherwise we need to move this to Makefile.arm64.

D'oh. Sorry, I completely missed that bit. Of course we want to test on 32bit ARM as well! I'll fix it up :).

[...]

Quoted 20 lines

Quoted 6 lines

arm/Makefile.common +6 -0

+static int rtc_fdt_init(void)
+{
+	const struct fdt_property *prop;
+	const void *fdt = dt_fdt();
+	int node, len;
+	u32 *data;

arm/Makefile.common tests-common += $(TEST_DIR)/pmu.flat

Quoted 10 lines

arm/Makefile.common +10 -0

+
+	node = fdt_node_offset_by_compatible(fdt, -1, "arm,pl031");
+	if (node < 0)
+		return -1;
+
+	prop = fdt_get_property(fdt, node, "interrupts", &len);
+	assert(prop && len == (3 * sizeof(u32)));
+	data = (u32 *)prop->data;
+	assert(data[0] == 0); /* SPI */
+	pl031_irq = SPI(fdt32_to_cpu(data[1]));

Nit: Ideally we'd add some more devicetree API to get interrupts. With that, and the existing devicetree API, we could remove all low-level fdt related code in this function.

Quoted 3 lines

Well, we probably want some really high level fdt API that can traverse reg properly to map bus regs into physical addresses. As long as we don't have all that magic,

We do have much of that magic already. Skim through lib/devicetree.h to see what's available.

Quoted 4 lines

I see little point in inventing anything that looks more sophisticated but doesn't actually take the difficult problems into account :).

Well, for this case, the "interrupts" decoding isn't difficult and could be shared among other devices if we added it to devicetree.c. And the reg decoding below to get the base address is already supported by the devicetree API.

All that said, it's just a nit that I won't insist on though, because it's hard enough to get unit test contributors without asking that they also contribute to the framework.