[PATCH v4 3/8] riscv: Rework Andes PLMT as a UCLASS_TIMER driver

Sean Anderson
2020-09-09T20:09:25Z

This converts the PLMT driver from the riscv-specific timer interface to be
a DM-based UCLASS_TIMER driver.

The clock-frequency/clocks properties are preferred over timebase-frequency
for two reasons. First, properties which affect a device should be located
near its binding in the device tree. Using timebase-frequency only really
makes sense when the cpu itself is the timer device. This is the case when
we read the time from a CSR, but not when there is a separate device.
Second, it lets the device use the clock subsystem which adds flexibility.
If the device is configured for a different clock speed, the timer can
adjust itself.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Rick Chen <rick@andestech.com>
---
This patch builds but has NOT been tested.

Changes in v4:
- Use timer_timebase_fallback

arch/riscv/Kconfig | 4 ---
arch/riscv/dts/ae350_32.dts | 1 +
arch/riscv/dts/ae350_64.dts | 1 +
arch/riscv/include/asm/global_data.h | 3 --
arch/riscv/lib/andes_plmt.c | 44 +++++++++++++---------------
5 files changed, 23 insertions(+), 30 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 21e6690f4d..d9155b9bab 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -177,10 +177,6 @@ config ANDES_PLIC
config ANDES_PLMT
bool
depends on RISCV_MMODE || SPL_RISCV_MMODE
- select REGMAP
- select SYSCON
- select SPL_REGMAP if SPL
- select SPL_SYSCON if SPL
help
The Andes PLMT block holds memory-mapped mtime register
associated with timer tick.
diff --git a/arch/riscv/dts/ae350_32.dts b/arch/riscv/dts/ae350_32.dts
index 3f8525fe56..afcb9cfbbf 100644
--- a/arch/riscv/dts/ae350_32.dts
+++ b/arch/riscv/dts/ae350_32.dts
@@ -162,6 +162,7 @@
&CPU2_intc 7
&CPU3_intc 7>;
reg = <0xe6000000 0x100000>;
+ clock-frequency = <60000000>;
};
};

diff --git a/arch/riscv/dts/ae350_64.dts b/arch/riscv/dts/ae350_64.dts
index 482c707503..1c37879049 100644
--- a/arch/riscv/dts/ae350_64.dts
+++ b/arch/riscv/dts/ae350_64.dts
@@ -162,6 +162,7 @@
&CPU2_intc 7
&CPU3_intc 7>;
reg = <0x0 0xe6000000 0x0 0x100000>;
+ clock-frequency = <60000000>;
};
};

diff --git a/arch/riscv/include/asm/global_data.h b/arch/riscv/include/asm/global_data.h
index 2eb14815bc..0dec5e669e 100644
--- a/arch/riscv/include/asm/global_data.h
+++ b/arch/riscv/include/asm/global_data.h
@@ -24,9 +24,6 @@ struct arch_global_data {
#ifdef CONFIG_ANDES_PLIC
void __iomem *plic; /* plic base address */
#endif
-#ifdef CONFIG_ANDES_PLMT
- void __iomem *plmt; /* plmt base address */
-#endif
#if CONFIG_IS_ENABLED(SMP)
struct ipi_data ipi[CONFIG_NR_CPUS];
#endif
diff --git a/arch/riscv/lib/andes_plmt.c b/arch/riscv/lib/andes_plmt.c
index a7e90ca992..a28c14c1eb 100644
--- a/arch/riscv/lib/andes_plmt.c
+++ b/arch/riscv/lib/andes_plmt.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2019, Rick Chen <rick@andestech.com>
+ * Copyright (C) 2020, Sean Anderson <seanga2@gmail.com>
*
* U-Boot syscon driver for Andes's Platform Level Machine Timer (PLMT).
* The PLMT block holds memory-mapped mtime register
@@ -9,46 +10,43 @@

#include <common.h>
#include <dm.h>
-#include <regmap.h>
-#include <syscon.h>
+#include <timer.h>
#include <asm/io.h>
-#include <asm/syscon.h>
#include <linux/err.h>

/* mtime register */
#define MTIME_REG(base) ((ulong)(base))

-DECLARE_GLOBAL_DATA_PTR;
-
-#define PLMT_BASE_GET(void) \
- do { \
- long *ret; \
- \
- if (!gd->arch.plmt) { \
- ret = syscon_get_first_range(RISCV_SYSCON_PLMT); \
- if (IS_ERR(ret)) \
- return PTR_ERR(ret); \
- gd->arch.plmt = ret; \
- } \
- } while (0)
-
-int riscv_get_time(u64 *time)
+static int andes_plmt_get_count(struct udevice *dev, u64 *count)
{
- PLMT_BASE_GET();
-
- *time = readq((void __iomem *)MTIME_REG(gd->arch.plmt));
+ *count = readq((void __iomem *)MTIME_REG(dev->priv));

return 0;
}

+static const struct timer_ops andes_plmt_ops = {
+ .get_count = andes_plmt_get_count,
+};
+
+static int andes_plmt_probe(struct udevice *dev)
+{
+ dev->priv = dev_read_addr_ptr(dev);
+ if (!dev->priv)
+ return -EINVAL;
+
+ return timer_timebase_fallback(dev);
+}
+
static const struct udevice_id andes_plmt_ids[] = {
- { .compatible = "riscv,plmt0", .data = RISCV_SYSCON_PLMT },
+ { .compatible = "riscv,plmt0" },
{ }
};

U_BOOT_DRIVER(andes_plmt) = {
.name = "andes_plmt",
- .id = UCLASS_SYSCON,
+ .id = UCLASS_TIMER,
.of_match = andes_plmt_ids,
+ .ops = &andes_plmt_ops,
+ .probe = andes_plmt_probe,
.flags = DM_FLAG_PRE_RELOC,
};
--
2.28.0