timer: Add driver for Nomadik Multi Timer Unit (MTU)
The Nomadik Multi Timer Unit (MTU) provides 4 decrementing
free-running timers. It is used in ST-Ericsson Ux500 SoCs.
The driver uses the first timer to implement UCLASS_TIMER.
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/timer/Kconfig b/drivers/timer/Kconfig
index 96cc492..6370244 100644
--- a/drivers/timer/Kconfig
+++ b/drivers/timer/Kconfig
@@ -127,6 +127,15 @@
hardware ways, nor got from device tree at the time when device
tree is not available yet.
+config NOMADIK_MTU_TIMER
+ bool "Nomadik MTU Timer"
+ depends on TIMER
+ help
+ Enables support for the Nomadik Multi Timer Unit (MTU),
+ used in ST-Ericsson Ux500 SoCs.
+ The MTU provides 4 decrementing free-running timers.
+ At the moment, only the first timer is used by the driver.
+
config OMAP_TIMER
bool "Omap timer support"
depends on TIMER
diff --git a/drivers/timer/Makefile b/drivers/timer/Makefile
index fa35bea..c22ffeb 100644
--- a/drivers/timer/Makefile
+++ b/drivers/timer/Makefile
@@ -12,6 +12,7 @@
obj-$(CONFIG_CADENCE_TTC_TIMER) += cadence-ttc.o
obj-$(CONFIG_DESIGNWARE_APB_TIMER) += dw-apb-timer.o
obj-$(CONFIG_MPC83XX_TIMER) += mpc83xx_timer.o
+obj-$(CONFIG_NOMADIK_MTU_TIMER) += nomadik-mtu-timer.o
obj-$(CONFIG_OMAP_TIMER) += omap-timer.o
obj-$(CONFIG_RENESAS_OSTM_TIMER) += ostm_timer.o
obj-$(CONFIG_RISCV_TIMER) += riscv_timer.o
diff --git a/drivers/timer/nomadik-mtu-timer.c b/drivers/timer/nomadik-mtu-timer.c
new file mode 100644
index 0000000..8648f1f
--- /dev/null
+++ b/drivers/timer/nomadik-mtu-timer.c
@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2019 Stephan Gerhold <stephan@gerhold.net>
+ *
+ * Based on arch/arm/cpu/armv7/u8500/timer.c:
+ * Copyright (C) 2010 Linaro Limited
+ * John Rigby <john.rigby@linaro.org>
+ *
+ * Based on Linux kernel source and internal ST-Ericsson U-Boot source:
+ * Copyright (C) 2009 Alessandro Rubini
+ * Copyright (C) 2010 ST-Ericsson
+ * Copyright (C) 2010 Linus Walleij for ST-Ericsson
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <timer.h>
+#include <asm/io.h>
+
+#define MTU_NUM_TIMERS 4
+
+/* The timers */
+struct nomadik_mtu_timer_regs {
+ u32 lr; /* Load register */
+ u32 cv; /* Current value */
+ u32 cr; /* Control register */
+ u32 bglr; /* Background load register */
+};
+
+/* The MTU that contains the timers */
+struct nomadik_mtu_regs {
+ u32 imsc; /* Interrupt mask set/clear */
+ u32 ris; /* Raw interrupt status */
+ u32 mis; /* Masked interrupt status */
+ u32 icr; /* Interrupt clear register */
+
+ struct nomadik_mtu_timer_regs timers[MTU_NUM_TIMERS];
+};
+
+/* Bits for the control register */
+#define MTU_CR_ONESHOT BIT(0) /* if 0 = wraps reloading from BGLR */
+#define MTU_CR_32BITS BIT(1) /* if 0 = 16-bit counter */
+
+#define MTU_CR_PRESCALE_SHIFT 2
+#define MTU_CR_PRESCALE_1 (0 << MTU_CR_PRESCALE_SHIFT)
+#define MTU_CR_PRESCALE_16 (1 << MTU_CR_PRESCALE_SHIFT)
+#define MTU_CR_PRESCALE_256 (2 << MTU_CR_PRESCALE_SHIFT)
+
+#define MTU_CR_PERIODIC BIT(6) /* if 0 = free-running */
+#define MTU_CR_ENABLE BIT(7)
+
+struct nomadik_mtu_priv {
+ struct nomadik_mtu_timer_regs *timer;
+};
+
+static int nomadik_mtu_get_count(struct udevice *dev, u64 *count)
+{
+ struct nomadik_mtu_priv *priv = dev_get_priv(dev);
+
+ /* Decrementing counter: invert the value */
+ *count = timer_conv_64(~readl(&priv->timer->cv));
+
+ return 0;
+}
+
+static int nomadik_mtu_probe(struct udevice *dev)
+{
+ struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+ struct nomadik_mtu_priv *priv = dev_get_priv(dev);
+ struct nomadik_mtu_regs *mtu;
+ fdt_addr_t addr;
+ u32 prescale;
+
+ addr = dev_read_addr(dev);
+ if (addr == FDT_ADDR_T_NONE)
+ return -EINVAL;
+
+ mtu = (struct nomadik_mtu_regs *)addr;
+ priv->timer = mtu->timers; /* Use first timer */
+
+ if (!uc_priv->clock_rate)
+ return -EINVAL;
+
+ /* Use divide-by-16 counter if tick rate is more than 32 MHz */
+ if (uc_priv->clock_rate > 32000000) {
+ uc_priv->clock_rate /= 16;
+ prescale = MTU_CR_PRESCALE_16;
+ } else {
+ prescale = MTU_CR_PRESCALE_1;
+ }
+
+ /* Configure a free-running, auto-wrap counter with selected prescale */
+ writel(MTU_CR_ENABLE | prescale | MTU_CR_32BITS, &priv->timer->cr);
+
+ return 0;
+}
+
+static const struct timer_ops nomadik_mtu_ops = {
+ .get_count = nomadik_mtu_get_count,
+};
+
+static const struct udevice_id nomadik_mtu_ids[] = {
+ { .compatible = "st,nomadik-mtu" },
+ {}
+};
+
+U_BOOT_DRIVER(nomadik_mtu) = {
+ .name = "nomadik_mtu",
+ .id = UCLASS_TIMER,
+ .of_match = nomadik_mtu_ids,
+ .priv_auto_alloc_size = sizeof(struct nomadik_mtu_priv),
+ .probe = nomadik_mtu_probe,
+ .ops = &nomadik_mtu_ops,
+};