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Subject[PATCH v9 05/27] clocksource: Add driver for the Ingenic JZ47xx OST
Date
From: Maarten ter Huurne <maarten@treewalker.org>

OST is the OS Timer, a 64-bit timer/counter with buffered reading.

SoCs before the JZ4770 had (if any) a 32-bit OST; the JZ4770 and
JZ4780 have a 64-bit OST.

This driver will register both a clocksource and a sched_clock to the
system.

Signed-off-by: Maarten ter Huurne <maarten@treewalker.org>
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---

Notes:
v5: New patch

v6: - Get rid of SoC IDs; pass pointer to ingenic_ost_soc_info as
devicetree match data instead.
- Use device_get_match_data() instead of the of_* variant
- Handle error of dev_get_regmap() properly

v7: Fix section mismatch by using builtin_platform_driver_probe()

v8: builtin_platform_driver_probe() does not work anymore in
4.20-rc6? The probe function won't be called. Work around this
for now by using late_initcall.

v9: No change

drivers/clocksource/Kconfig | 8 ++
drivers/clocksource/Makefile | 1 +
drivers/clocksource/ingenic-ost.c | 215 ++++++++++++++++++++++++++++++++++++++
3 files changed, 224 insertions(+)
create mode 100644 drivers/clocksource/ingenic-ost.c

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 4e69af15c3e7..e0646878b0de 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -648,4 +648,12 @@ config INGENIC_TIMER
help
Support for the timer/counter unit of the Ingenic JZ SoCs.

+config INGENIC_OST
+ bool "Ingenic JZ47xx Operating System Timer"
+ depends on MIPS || COMPILE_TEST
+ depends on COMMON_CLK
+ select INGENIC_TIMER
+ help
+ Support for the OS Timer of the Ingenic JZ4770 or similar SoC.
+
endmenu
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 7c8f790dcf67..7faa8108574a 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -75,6 +75,7 @@ obj-$(CONFIG_ASM9260_TIMER) += asm9260_timer.o
obj-$(CONFIG_H8300_TMR8) += h8300_timer8.o
obj-$(CONFIG_H8300_TMR16) += h8300_timer16.o
obj-$(CONFIG_H8300_TPU) += h8300_tpu.o
+obj-$(CONFIG_INGENIC_OST) += ingenic-ost.o
obj-$(CONFIG_INGENIC_TIMER) += ingenic-timer.o
obj-$(CONFIG_CLKSRC_ST_LPC) += clksrc_st_lpc.o
obj-$(CONFIG_X86_NUMACHIP) += numachip.o
diff --git a/drivers/clocksource/ingenic-ost.c b/drivers/clocksource/ingenic-ost.c
new file mode 100644
index 000000000000..cc0fee3efd29
--- /dev/null
+++ b/drivers/clocksource/ingenic-ost.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * JZ47xx SoCs TCU Operating System Timer driver
+ *
+ * Copyright (C) 2016 Maarten ter Huurne <maarten@treewalker.org>
+ * Copyright (C) 2018 Paul Cercueil <paul@crapouillou.net>
+ */
+
+#include <linux/clk.h>
+#include <linux/clocksource.h>
+#include <linux/mfd/ingenic-tcu.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+#include <linux/regmap.h>
+#include <linux/sched_clock.h>
+
+#include "ingenic-timer.h"
+
+#define TCU_OST_TCSR_MASK 0xc0
+#define TCU_OST_TCSR_CNT_MD BIT(15)
+
+#define TCU_OST_CHANNEL 15
+
+struct ingenic_ost_soc_info {
+ bool is64bit;
+};
+
+struct ingenic_ost {
+ struct regmap *map;
+ struct clk *clk;
+
+ struct clocksource cs;
+};
+
+static u64 notrace ingenic_ost_read_cntl(void)
+{
+ /* Bypass the regmap here as we must return as soon as possible */
+ return readl(ingenic_tcu_base + TCU_REG_OST_CNTL);
+}
+
+static u64 notrace ingenic_ost_read_cnth(void)
+{
+ /* Bypass the regmap here as we must return as soon as possible */
+ return readl(ingenic_tcu_base + TCU_REG_OST_CNTH);
+}
+
+static u64 notrace ingenic_ost_clocksource_read(struct clocksource *cs)
+{
+ u32 val1, val2;
+ u64 count, recount;
+ s64 diff;
+
+ /*
+ * The buffering of the upper 32 bits of the timer prevents wrong
+ * results from the bottom 32 bits overflowing due to the timer ticking
+ * along. However, it does not prevent wrong results from simultaneous
+ * reads of the timer, which could reset the buffer mid-read.
+ * Since this kind of wrong read can happen only when the bottom bits
+ * overflow, there will be minutes between wrong reads, so if we read
+ * twice in succession, at least one of the reads will be correct.
+ */
+
+ /* Bypass the regmap here as we must return as soon as possible */
+ val1 = readl(ingenic_tcu_base + TCU_REG_OST_CNTL);
+ val2 = readl(ingenic_tcu_base + TCU_REG_OST_CNTHBUF);
+ count = (u64)val1 | (u64)val2 << 32;
+
+ val1 = readl(ingenic_tcu_base + TCU_REG_OST_CNTL);
+ val2 = readl(ingenic_tcu_base + TCU_REG_OST_CNTHBUF);
+ recount = (u64)val1 | (u64)val2 << 32;
+
+ /*
+ * A wrong read will produce a result that is 1<<32 too high: the bottom
+ * part from before overflow and the upper part from after overflow.
+ * Therefore, the lower value of the two reads is the correct value.
+ */
+
+ diff = (s64)(recount - count);
+ if (unlikely(diff < 0))
+ count = recount;
+
+ return count;
+}
+
+static int __init ingenic_ost_probe(struct platform_device *pdev)
+{
+ const struct ingenic_ost_soc_info *soc_info;
+ struct device *dev = &pdev->dev;
+ struct ingenic_ost *ost;
+ struct clocksource *cs;
+ unsigned long rate, flags;
+ int err;
+
+ soc_info = device_get_match_data(dev);
+ if (!soc_info)
+ return -EINVAL;
+
+ ost = devm_kzalloc(dev, sizeof(*ost), GFP_KERNEL);
+ if (!ost)
+ return -ENOMEM;
+
+ ost->map = dev_get_regmap(dev->parent, NULL);
+ if (!ost->map) {
+ dev_err(dev, "regmap not found\n");
+ return -EINVAL;
+ }
+
+ ost->clk = devm_clk_get(dev, "ost");
+ if (IS_ERR(ost->clk))
+ return PTR_ERR(ost->clk);
+
+ err = clk_prepare_enable(ost->clk);
+ if (err)
+ return err;
+
+ /* Clear counter high/low registers */
+ if (soc_info->is64bit)
+ regmap_write(ost->map, TCU_REG_OST_CNTL, 0);
+ regmap_write(ost->map, TCU_REG_OST_CNTH, 0);
+
+ /* Don't reset counter at compare value. */
+ regmap_update_bits(ost->map, TCU_REG_OST_TCSR,
+ TCU_OST_TCSR_MASK, TCU_OST_TCSR_CNT_MD);
+
+ rate = clk_get_rate(ost->clk);
+
+ /* Enable OST TCU channel */
+ regmap_write(ost->map, TCU_REG_TESR, BIT(TCU_OST_CHANNEL));
+
+ cs = &ost->cs;
+ cs->name = "ingenic-ost";
+ cs->rating = 320;
+ cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
+
+ if (soc_info->is64bit) {
+ cs->mask = CLOCKSOURCE_MASK(64);
+ cs->read = ingenic_ost_clocksource_read;
+ } else {
+ cs->mask = CLOCKSOURCE_MASK(32);
+ cs->read = (u64 (*)(struct clocksource *))ingenic_ost_read_cnth;
+ }
+
+ err = clocksource_register_hz(cs, rate);
+ if (err) {
+ dev_err(dev, "clocksource registration failed: %d\n", err);
+ clk_disable_unprepare(ost->clk);
+ return err;
+ }
+
+ /* Cannot register a sched_clock with interrupts on */
+ local_irq_save(flags);
+ if (soc_info->is64bit)
+ sched_clock_register(ingenic_ost_read_cntl, 32, rate);
+ else
+ sched_clock_register(ingenic_ost_read_cnth, 32, rate);
+ local_irq_restore(flags);
+
+ return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int ingenic_ost_suspend(struct device *dev)
+{
+ struct ingenic_ost *ost = dev_get_drvdata(dev);
+
+ clk_disable(ost->clk);
+ return 0;
+}
+
+static int ingenic_ost_resume(struct device *dev)
+{
+ struct ingenic_ost *ost = dev_get_drvdata(dev);
+
+ return clk_enable(ost->clk);
+}
+
+static SIMPLE_DEV_PM_OPS(ingenic_ost_pm_ops, ingenic_ost_suspend,
+ ingenic_ost_resume);
+#define INGENIC_OST_PM_OPS (&ingenic_ost_pm_ops)
+#else
+#define INGENIC_OST_PM_OPS NULL
+#endif /* CONFIG_PM_SUSPEND */
+
+static const struct ingenic_ost_soc_info jz4725b_ost_soc_info = {
+ .is64bit = false,
+};
+
+static const struct ingenic_ost_soc_info jz4770_ost_soc_info = {
+ .is64bit = true,
+};
+
+static const struct of_device_id ingenic_ost_of_match[] = {
+ { .compatible = "ingenic,jz4725b-ost", .data = &jz4725b_ost_soc_info, },
+ { .compatible = "ingenic,jz4770-ost", .data = &jz4770_ost_soc_info, },
+ { }
+};
+
+static struct platform_driver ingenic_ost_driver = {
+ .driver = {
+ .name = "ingenic-ost",
+ .pm = INGENIC_OST_PM_OPS,
+ .of_match_table = ingenic_ost_of_match,
+ },
+};
+
+/* FIXME: Using device_initcall (or buildin_platform_driver_probe) results
+ * in the driver not being probed at all. It worked in 4.18...
+ */
+static int __init ingenic_ost_drv_register(void)
+{
+ return platform_driver_probe(&ingenic_ost_driver,
+ ingenic_ost_probe);
+}
+late_initcall(ingenic_ost_drv_register);
--
2.11.0
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