[PATCH v4 1/3] timer: atmel_tcb_timer: add atmel_tcb driver

Clément Léger
2022-03-04T09:47:05Z

Add a driver for the timer counter block that can be found on sama5d2.
This driver will be used when booting under OP-TEE since the pit timer
which is part of the SYSC is secured. Channel 1 & 2 are configured to
be chained together which allows to have a 64bits counter.

Signed-off-by: Clément Léger <clement.leger@bootlin.com>
---
MAINTAINERS | 1 +
drivers/timer/Kconfig | 8 ++
drivers/timer/Makefile | 1 +
drivers/timer/atmel_tcb_timer.c | 155 ++++++++++++++++++++++++++++++++
4 files changed, 165 insertions(+)
create mode 100644 drivers/timer/atmel_tcb_timer.c

diff --git a/MAINTAINERS b/MAINTAINERS
index fb171e0c68..73b46c4631 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -352,6 +352,7 @@ F: arch/arm/mach-at91/
F: board/atmel/
F: drivers/cpu/at91_cpu.c
F: drivers/misc/microchip_flexcom.c
+F: drivers/timer/atmel_tcb_timer.c
F: include/dt-bindings/mfd/atmel-flexcom.h
F: drivers/timer/mchp-pit64b-timer.c

diff --git a/drivers/timer/Kconfig b/drivers/timer/Kconfig
index 8913142654..8fad59b81a 100644
--- a/drivers/timer/Kconfig
+++ b/drivers/timer/Kconfig
@@ -96,6 +96,14 @@ config ATMEL_PIT_TIMER
it is designed to offer maximum accuracy and efficient management,
even for systems with long response time.

+config ATMEL_TCB_TIMER
+ bool "Atmel timer counter support"
+ depends on TIMER
+ depends on ARCH_AT91
+ help
+ Select this to enable the use of the timer counter as a monotonic
+ counter.
+
config CADENCE_TTC_TIMER
bool "Cadence TTC (Triple Timer Counter)"
depends on TIMER
diff --git a/drivers/timer/Makefile b/drivers/timer/Makefile
index e2bd530eb0..58da6c1e84 100644
--- a/drivers/timer/Makefile
+++ b/drivers/timer/Makefile
@@ -10,6 +10,7 @@ obj-$(CONFIG_ARC_TIMER) += arc_timer.o
obj-$(CONFIG_AST_TIMER) += ast_timer.o
obj-$(CONFIG_ATCPIT100_TIMER) += atcpit100_timer.o
obj-$(CONFIG_ATMEL_PIT_TIMER) += atmel_pit_timer.o
+obj-$(CONFIG_ATMEL_TCB_TIMER) += atmel_tcb_timer.o
obj-$(CONFIG_CADENCE_TTC_TIMER) += cadence-ttc.o
obj-$(CONFIG_DESIGNWARE_APB_TIMER) += dw-apb-timer.o
obj-$(CONFIG_MPC83XX_TIMER) += mpc83xx_timer.o
diff --git a/drivers/timer/atmel_tcb_timer.c b/drivers/timer/atmel_tcb_timer.c
new file mode 100644
index 0000000000..b73b367227
--- /dev/null
+++ b/drivers/timer/atmel_tcb_timer.c
@@ -0,0 +1,155 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2022 Microchip Corporation
+ *
+ * Author: Clément Léger <clement.leger@bootlin.com>
+ */
+
+#include <common.h>
+#include <clk.h>
+#include <dm.h>
+#include <timer.h>
+#include <asm/io.h>
+#include <linux/bitops.h>
+
+#define TCB_CHAN(chan) ((chan) * 0x40)
+
+#define TCB_CCR(chan) (0x0 + TCB_CHAN(chan))
+#define TCB_CCR_SWTRG 0x4
+#define TCB_CCR_CLKEN 0x1
+
+#define TCB_CMR(chan) (0x4 + TCB_CHAN(chan))
+#define TCB_CMR_WAVE BIT(15)
+#define TCB_CMR_TIMER_CLOCK0 0
+#define TCB_CMR_XC1 6
+#define TCB_CMR_ACPA_SET BIT(16)
+#define TCB_CMR_ACPC_CLEAR (2 << 18)
+
+#define TCB_CV(chan) (0x10 + TCB_CHAN(chan))
+
+#define TCB_RA(chan) (0x14 + TCB_CHAN(chan))
+#define TCB_RC(chan) (0x1c + TCB_CHAN(chan))
+
+#define TCB_IDR(chan) (0x28 + TCB_CHAN(chan))
+
+#define TCB_BCR 0xc0
+#define TCB_BCR_SYNC 0x1
+
+#define TCB_BMR 0xc4
+#define TCB_BMR_TC1XC1S_TIOA0 (2 << 2)
+
+#define TCB_WPMR 0xe4
+#define TCB_WPMR_WAKEY 0x54494d
+
+struct atmel_tcb_plat {
+ void __iomem *base;
+};
+
+static u64 atmel_tcb_get_count(struct udevice *dev)
+{
+ struct atmel_tcb_plat *plat = dev_get_plat(dev);
+ u64 cv0 = 0;
+ u64 cv1 = 0;
+
+ do {
+ cv1 = readl(plat->base + TCB_CV(1));
+ cv0 = readl(plat->base + TCB_CV(0));
+ } while (readl(plat->base + TCB_CV(1)) != cv1);
+
+ cv0 |= cv1 << 32;
+
+ return cv0;
+}
+
+static void atmel_tcb_configure(void __iomem *base)
+{
+ /* Disable write protection */
+ writel(TCB_WPMR_WAKEY, base + TCB_WPMR);
+
+ /* Disable all irqs for both channel 0 & 1 */
+ writel(0xff, base + TCB_IDR(0));
+ writel(0xff, base + TCB_IDR(1));
+
+ /*
+ * In order to avoid wrapping, use a 64 bit counter by chaining
+ * two channels.
+ * Channel 0 is configured to generate a clock on TIOA0 which is cleared
+ * when reaching 0x80000000 and set when reaching 0.
+ */
+ writel(TCB_CMR_TIMER_CLOCK0 | TCB_CMR_WAVE | TCB_CMR_ACPA_SET
+ | TCB_CMR_ACPC_CLEAR, base + TCB_CMR(0));
+ writel(0x80000000, base + TCB_RC(0));
+ writel(0x1, base + TCB_RA(0));
+ writel(TCB_CCR_CLKEN, base + TCB_CCR(0));
+
+ /* Channel 1 is configured to use TIOA0 as input */
+ writel(TCB_CMR_XC1 | TCB_CMR_WAVE, base + TCB_CMR(1));
+ writel(TCB_CCR_CLKEN, base + TCB_CCR(1));
+
+ /* Set XC1 input to be TIOA0 (ie output of Channel 0) */
+ writel(TCB_BMR_TC1XC1S_TIOA0, base + TCB_BMR);
+
+ /* Sync & start all timers */
+ writel(TCB_BCR_SYNC, base + TCB_BCR);
+}
+
+static int atmel_tcb_probe(struct udevice *dev)
+{
+ struct atmel_tcb_plat *plat = dev_get_plat(dev);
+ struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+ struct clk clk;
+ ulong clk_rate;
+ int ret;
+
+ if (!device_is_compatible(dev->parent, "atmel,sama5d2-tcb"))
+ return -EINVAL;
+
+ /* Currently, we only support channel 0 and 1 to be chained */
+ if (dev_read_addr_index(dev, 0) != 0 &&
+ dev_read_addr_index(dev, 1) != 1) {
+ printf("Error: only chained timers 0 and 1 are supported\n");
+ return -EINVAL;
+ }
+
+ ret = clk_get_by_name(dev->parent, "gclk", &clk);
+ if (ret)
+ return -EINVAL;
+
+ clk_rate = clk_get_rate(&clk);
+ if (!clk_rate)
+ return -EINVAL;
+
+ uc_priv->clock_rate = clk_rate;
+
+ atmel_tcb_configure(plat->base);
+
+ return 0;
+}
+
+static int atmel_tcb_of_to_plat(struct udevice *dev)
+{
+ struct atmel_tcb_plat *plat = dev_get_plat(dev);
+
+ plat->base = dev_read_addr_ptr(dev->parent);
+
+ return 0;
+}
+
+static const struct timer_ops atmel_tcb_ops = {
+ .get_count = atmel_tcb_get_count,
+};
+
+static const struct udevice_id atmel_tcb_ids[] = {
+ { .compatible = "atmel,tcb-timer" },
+ { }
+};
+
+U_BOOT_DRIVER(atmel_tcb) = {
+ .name = "atmel_tcb",
+ .id = UCLASS_TIMER,
+ .of_match = atmel_tcb_ids,
+ .of_to_plat = atmel_tcb_of_to_plat,
+ .plat_auto = sizeof(struct atmel_tcb_plat),
+ .probe = atmel_tcb_probe,
+ .ops = &atmel_tcb_ops,
+};
--
2.34.1