Merge tag 'y2038' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground into timers/core

Pull more y2038 work from Arnd Bergman:

y2038: convert more syscalls

Here is another set of system call changes to prepare the change over to
64-bit time_t. As before, the strategy is to change system calls that
take a 'struct timespec' argument over to 'struct __kernel_timespec',
which for now is defined to be the same but will get redefined to use a
64-bit time_t argument once we are ready to modify the system call tables.

The major change from previous patches is that the plan is no longer
to directly use the 'compat' system calls for providing compatibility
with the existing 32-bit time_t based entry points. Instead, we rename
the compat code to something that makes more sense on 32-bit architectures,
e.g. compat_timespec becomes old_timespec32.

With the renamed types in place, change over the 'stat' and 'utimes'
families of system calls, sched_rr_get_interval, recvmmsg and
rt_sigtimedwait. Another series for poll, select and io_pgetevents is
currently being tested.

4 files changed, 118 insertions, 1 deletions

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index dec0dd88ec15..a11f4ba98b05 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -609,4 +609,15 @@ config ATCPIT100_TIMER
 	help
 	  This option enables support for the Andestech ATCPIT100 timers.
 
+config RISCV_TIMER
+	bool "Timer for the RISC-V platform"
+	depends on RISCV
+	default y
+	select TIMER_PROBE
+	select TIMER_OF
+	help
+	  This enables the per-hart timer built into all RISC-V systems, which
+	  is accessed via both the SBI and the rdcycle instruction.  This is
+	  required for all RISC-V systems.
+
 endmenu
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index c070cc7992e9..db51b2427e8a 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -78,3 +78,4 @@ obj-$(CONFIG_H8300_TPU)			+= h8300_tpu.o
 obj-$(CONFIG_CLKSRC_ST_LPC)		+= clksrc_st_lpc.o
 obj-$(CONFIG_X86_NUMACHIP)		+= numachip.o
 obj-$(CONFIG_ATCPIT100_TIMER)		+= timer-atcpit100.o
+obj-$(CONFIG_RISCV_TIMER)		+= riscv_timer.o
diff --git a/drivers/clocksource/riscv_timer.c b/drivers/clocksource/riscv_timer.c
new file mode 100644
index 000000000000..4e8b347e43e2
--- /dev/null
+++ b/drivers/clocksource/riscv_timer.c
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2012 Regents of the University of California
+ * Copyright (C) 2017 SiFive
+ */
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/cpu.h>
+#include <linux/delay.h>
+#include <linux/irq.h>
+#include <asm/sbi.h>
+
+/*
+ * All RISC-V systems have a timer attached to every hart.  These timers can be
+ * read by the 'rdcycle' pseudo instruction, and can use the SBI to setup
+ * events.  In order to abstract the architecture-specific timer reading and
+ * setting functions away from the clock event insertion code, we provide
+ * function pointers to the clockevent subsystem that perform two basic
+ * operations: rdtime() reads the timer on the current CPU, and
+ * next_event(delta) sets the next timer event to 'delta' cycles in the future.
+ * As the timers are inherently a per-cpu resource, these callbacks perform
+ * operations on the current hart.  There is guaranteed to be exactly one timer
+ * per hart on all RISC-V systems.
+ */
+
+static int riscv_clock_next_event(unsigned long delta,
+		struct clock_event_device *ce)
+{
+	csr_set(sie, SIE_STIE);
+	sbi_set_timer(get_cycles64() + delta);
+	return 0;
+}
+
+static DEFINE_PER_CPU(struct clock_event_device, riscv_clock_event) = {
+	.name			= "riscv_timer_clockevent",
+	.features		= CLOCK_EVT_FEAT_ONESHOT,
+	.rating			= 100,
+	.set_next_event		= riscv_clock_next_event,
+};
+
+/*
+ * It is guaranteed that all the timers across all the harts are synchronized
+ * within one tick of each other, so while this could technically go
+ * backwards when hopping between CPUs, practically it won't happen.
+ */
+static unsigned long long riscv_clocksource_rdtime(struct clocksource *cs)
+{
+	return get_cycles64();
+}
+
+static DEFINE_PER_CPU(struct clocksource, riscv_clocksource) = {
+	.name		= "riscv_clocksource",
+	.rating		= 300,
+	.mask		= CLOCKSOURCE_MASK(BITS_PER_LONG),
+	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
+	.read		= riscv_clocksource_rdtime,
+};
+
+static int riscv_timer_starting_cpu(unsigned int cpu)
+{
+	struct clock_event_device *ce = per_cpu_ptr(&riscv_clock_event, cpu);
+
+	ce->cpumask = cpumask_of(cpu);
+	clockevents_config_and_register(ce, riscv_timebase, 100, 0x7fffffff);
+
+	csr_set(sie, SIE_STIE);
+	return 0;
+}
+
+static int riscv_timer_dying_cpu(unsigned int cpu)
+{
+	csr_clear(sie, SIE_STIE);
+	return 0;
+}
+
+/* called directly from the low-level interrupt handler */
+void riscv_timer_interrupt(void)
+{
+	struct clock_event_device *evdev = this_cpu_ptr(&riscv_clock_event);
+
+	csr_clear(sie, SIE_STIE);
+	evdev->event_handler(evdev);
+}
+
+static int __init riscv_timer_init_dt(struct device_node *n)
+{
+	int cpu_id = riscv_of_processor_hart(n), error;
+	struct clocksource *cs;
+
+	if (cpu_id != smp_processor_id())
+		return 0;
+
+	cs = per_cpu_ptr(&riscv_clocksource, cpu_id);
+	clocksource_register_hz(cs, riscv_timebase);
+
+	error = cpuhp_setup_state(CPUHP_AP_RISCV_TIMER_STARTING,
+			 "clockevents/riscv/timer:starting",
+			 riscv_timer_starting_cpu, riscv_timer_dying_cpu);
+	if (error)
+		pr_err("RISCV timer register failed [%d] for cpu = [%d]\n",
+		       error, cpu_id);
+	return error;
+}
+
+TIMER_OF_DECLARE(riscv_timer, "riscv", riscv_timer_init_dt);
diff --git a/drivers/clocksource/tegra20_timer.c b/drivers/clocksource/tegra20_timer.c
index dabf0a103567..aa624885e0e2 100644
--- a/drivers/clocksource/tegra20_timer.c
+++ b/drivers/clocksource/tegra20_timer.c
@@ -259,6 +259,6 @@ static int __init tegra20_init_rtc(struct device_node *np)
 	else
 		clk_prepare_enable(clk);
 
-	return register_persistent_clock(NULL, tegra_read_persistent_clock64);
+	return register_persistent_clock(tegra_read_persistent_clock64);
 }
 TIMER_OF_DECLARE(tegra20_rtc, "nvidia,tegra20-rtc", tegra20_init_rtc);