[PATCH v6 4/9] riscv: Rework Andes PLMT as a UCLASS_TIMER driver

[Sean Anderson]

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 at gmail.com>
Reviewed-by: Rick Chen <rick at andestech.com>
---
This patch builds but has NOT been tested.

(no changes since v5)

Changes in v5:
- Remove RISCV_SYSCON_PLMT
- Undo changes to ae350 device trees. They are unnecessary with
  timer_timebase_fallback.

Changes in v4:
- Use timer_timebase_fallback

 arch/riscv/Kconfig                   |  4 ---
 arch/riscv/include/asm/global_data.h |  3 --
 arch/riscv/include/asm/syscon.h      |  4 +--
 arch/riscv/lib/andes_plmt.c          | 44 +++++++++++++---------------
 4 files changed, 23 insertions(+), 32 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/include/asm/global_data.h b/arch/riscv/include/asm/global_data.h
index b711fcc44d..d3a0b1d221 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/include/asm/syscon.h b/arch/riscv/include/asm/syscon.h
index 26a008ca59..c3629e4b53 100644
--- a/arch/riscv/include/asm/syscon.h
+++ b/arch/riscv/include/asm/syscon.h
@@ -7,13 +7,13 @@
 #define _ASM_SYSCON_H
 
 /*
- * System controllers in a RISC-V system
+ * System controllers in a RISC-V system. These should only be used for
+ * identifying IPI controllers. Other devices should use DM to probe.
  */
 enum {
 	RISCV_NONE,
 	RISCV_SYSCON_CLINT,	/* Core Local Interruptor (CLINT) */
 	RISCV_SYSCON_PLIC,	/* Platform Level Interrupt Controller (PLIC) */
-	RISCV_SYSCON_PLMT,	/* Platform Level Machine Timer (PLMT) */
 };
 
 #endif /* _ASM_SYSCON_H */
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 at andestech.com>
+ * Copyright (C) 2020, Sean Anderson <seanga2 at 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