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author | Linus Torvalds <torvalds@linux-foundation.org> | 2022-12-12 23:52:02 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-12-12 23:52:02 +0300 |
commit | 0a1d4434db5f86c50018fe0aab299ac97dc15b76 (patch) | |
tree | 69574d3ef27cbf6527bcc38cd035d8bdf854203c /drivers/clocksource/sh_cmt.c | |
parent | 79ad89123c2523a7982d457641dd64f339307e6c (diff) | |
parent | 18a207849218d8c15072f449e6d0b901262290c9 (diff) | |
download | linux-0a1d4434db5f86c50018fe0aab299ac97dc15b76.tar.xz |
Merge tag 'timers-core-2022-12-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Thomas Gleixner:
"Updates for timers, timekeeping and drivers:
Core:
- The timer_shutdown[_sync]() infrastructure:
Tearing down timers can be tedious when there are circular
dependencies to other things which need to be torn down. A prime
example is timer and workqueue where the timer schedules work and
the work arms the timer.
What needs to prevented is that pending work which is drained via
destroy_workqueue() does not rearm the previously shutdown timer.
Nothing in that shutdown sequence relies on the timer being
functional.
The conclusion was that the semantics of timer_shutdown_sync()
should be:
- timer is not enqueued
- timer callback is not running
- timer cannot be rearmed
Preventing the rearming of shutdown timers is done by discarding
rearm attempts silently.
A warning for the case that a rearm attempt of a shutdown timer is
detected would not be really helpful because it's entirely unclear
how it should be acted upon. The only way to address such a case is
to add 'if (in_shutdown)' conditionals all over the place. This is
error prone and in most cases of teardown not required all.
- The real fix for the bluetooth HCI teardown based on
timer_shutdown_sync().
A larger scale conversion to timer_shutdown_sync() is work in
progress.
- Consolidation of VDSO time namespace helper functions
- Small fixes for timer and timerqueue
Drivers:
- Prevent integer overflow on the XGene-1 TVAL register which causes
an never ending interrupt storm.
- The usual set of new device tree bindings
- Small fixes and improvements all over the place"
* tag 'timers-core-2022-12-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (34 commits)
dt-bindings: timer: renesas,cmt: Add r8a779g0 CMT support
dt-bindings: timer: renesas,tmu: Add r8a779g0 support
clocksource/drivers/arm_arch_timer: Use kstrtobool() instead of strtobool()
clocksource/drivers/timer-ti-dm: Fix missing clk_disable_unprepare in dmtimer_systimer_init_clock()
clocksource/drivers/timer-ti-dm: Clear settings on probe and free
clocksource/drivers/timer-ti-dm: Make timer_get_irq static
clocksource/drivers/timer-ti-dm: Fix warning for omap_timer_match
clocksource/drivers/arm_arch_timer: Fix XGene-1 TVAL register math error
clocksource/drivers/timer-npcm7xx: Enable timer 1 clock before use
dt-bindings: timer: nuvoton,npcm7xx-timer: Allow specifying all clocks
dt-bindings: timer: rockchip: Add rockchip,rk3128-timer
clockevents: Repair kernel-doc for clockevent_delta2ns()
clocksource/drivers/ingenic-ost: Define pm functions properly in platform_driver struct
clocksource/drivers/sh_cmt: Access registers according to spec
vdso/timens: Refactor copy-pasted find_timens_vvar_page() helper into one copy
Bluetooth: hci_qca: Fix the teardown problem for real
timers: Update the documentation to reflect on the new timer_shutdown() API
timers: Provide timer_shutdown[_sync]()
timers: Add shutdown mechanism to the internal functions
timers: Split [try_to_]del_timer[_sync]() to prepare for shutdown mode
...
Diffstat (limited to 'drivers/clocksource/sh_cmt.c')
-rw-r--r-- | drivers/clocksource/sh_cmt.c | 88 |
1 files changed, 55 insertions, 33 deletions
diff --git a/drivers/clocksource/sh_cmt.c b/drivers/clocksource/sh_cmt.c index 64dcb082d4cf..7b952aa52c0b 100644 --- a/drivers/clocksource/sh_cmt.c +++ b/drivers/clocksource/sh_cmt.c @@ -13,6 +13,7 @@ #include <linux/init.h> #include <linux/interrupt.h> #include <linux/io.h> +#include <linux/iopoll.h> #include <linux/ioport.h> #include <linux/irq.h> #include <linux/module.h> @@ -116,6 +117,7 @@ struct sh_cmt_device { void __iomem *mapbase; struct clk *clk; unsigned long rate; + unsigned int reg_delay; raw_spinlock_t lock; /* Protect the shared start/stop register */ @@ -247,10 +249,17 @@ static inline u32 sh_cmt_read_cmstr(struct sh_cmt_channel *ch) static inline void sh_cmt_write_cmstr(struct sh_cmt_channel *ch, u32 value) { - if (ch->iostart) - ch->cmt->info->write_control(ch->iostart, 0, value); - else - ch->cmt->info->write_control(ch->cmt->mapbase, 0, value); + u32 old_value = sh_cmt_read_cmstr(ch); + + if (value != old_value) { + if (ch->iostart) { + ch->cmt->info->write_control(ch->iostart, 0, value); + udelay(ch->cmt->reg_delay); + } else { + ch->cmt->info->write_control(ch->cmt->mapbase, 0, value); + udelay(ch->cmt->reg_delay); + } + } } static inline u32 sh_cmt_read_cmcsr(struct sh_cmt_channel *ch) @@ -260,7 +269,12 @@ static inline u32 sh_cmt_read_cmcsr(struct sh_cmt_channel *ch) static inline void sh_cmt_write_cmcsr(struct sh_cmt_channel *ch, u32 value) { - ch->cmt->info->write_control(ch->ioctrl, CMCSR, value); + u32 old_value = sh_cmt_read_cmcsr(ch); + + if (value != old_value) { + ch->cmt->info->write_control(ch->ioctrl, CMCSR, value); + udelay(ch->cmt->reg_delay); + } } static inline u32 sh_cmt_read_cmcnt(struct sh_cmt_channel *ch) @@ -268,14 +282,33 @@ static inline u32 sh_cmt_read_cmcnt(struct sh_cmt_channel *ch) return ch->cmt->info->read_count(ch->ioctrl, CMCNT); } -static inline void sh_cmt_write_cmcnt(struct sh_cmt_channel *ch, u32 value) +static inline int sh_cmt_write_cmcnt(struct sh_cmt_channel *ch, u32 value) { + /* Tests showed that we need to wait 3 clocks here */ + unsigned int cmcnt_delay = DIV_ROUND_UP(3 * ch->cmt->reg_delay, 2); + u32 reg; + + if (ch->cmt->info->model > SH_CMT_16BIT) { + int ret = read_poll_timeout_atomic(sh_cmt_read_cmcsr, reg, + !(reg & SH_CMT32_CMCSR_WRFLG), + 1, cmcnt_delay, false, ch); + if (ret < 0) + return ret; + } + ch->cmt->info->write_count(ch->ioctrl, CMCNT, value); + udelay(cmcnt_delay); + return 0; } static inline void sh_cmt_write_cmcor(struct sh_cmt_channel *ch, u32 value) { - ch->cmt->info->write_count(ch->ioctrl, CMCOR, value); + u32 old_value = ch->cmt->info->read_count(ch->ioctrl, CMCOR); + + if (value != old_value) { + ch->cmt->info->write_count(ch->ioctrl, CMCOR, value); + udelay(ch->cmt->reg_delay); + } } static u32 sh_cmt_get_counter(struct sh_cmt_channel *ch, u32 *has_wrapped) @@ -319,7 +352,7 @@ static void sh_cmt_start_stop_ch(struct sh_cmt_channel *ch, int start) static int sh_cmt_enable(struct sh_cmt_channel *ch) { - int k, ret; + int ret; dev_pm_syscore_device(&ch->cmt->pdev->dev, true); @@ -347,26 +380,9 @@ static int sh_cmt_enable(struct sh_cmt_channel *ch) } sh_cmt_write_cmcor(ch, 0xffffffff); - sh_cmt_write_cmcnt(ch, 0); - - /* - * According to the sh73a0 user's manual, as CMCNT can be operated - * only by the RCLK (Pseudo 32 kHz), there's one restriction on - * modifying CMCNT register; two RCLK cycles are necessary before - * this register is either read or any modification of the value - * it holds is reflected in the LSI's actual operation. - * - * While at it, we're supposed to clear out the CMCNT as of this - * moment, so make sure it's processed properly here. This will - * take RCLKx2 at maximum. - */ - for (k = 0; k < 100; k++) { - if (!sh_cmt_read_cmcnt(ch)) - break; - udelay(1); - } + ret = sh_cmt_write_cmcnt(ch, 0); - if (sh_cmt_read_cmcnt(ch)) { + if (ret || sh_cmt_read_cmcnt(ch)) { dev_err(&ch->cmt->pdev->dev, "ch%u: cannot clear CMCNT\n", ch->index); ret = -ETIMEDOUT; @@ -995,8 +1011,8 @@ MODULE_DEVICE_TABLE(of, sh_cmt_of_table); static int sh_cmt_setup(struct sh_cmt_device *cmt, struct platform_device *pdev) { - unsigned int mask; - unsigned int i; + unsigned int mask, i; + unsigned long rate; int ret; cmt->pdev = pdev; @@ -1032,10 +1048,16 @@ static int sh_cmt_setup(struct sh_cmt_device *cmt, struct platform_device *pdev) if (ret < 0) goto err_clk_unprepare; - if (cmt->info->width == 16) - cmt->rate = clk_get_rate(cmt->clk) / 512; - else - cmt->rate = clk_get_rate(cmt->clk) / 8; + rate = clk_get_rate(cmt->clk); + if (!rate) { + ret = -EINVAL; + goto err_clk_disable; + } + + /* We shall wait 2 input clks after register writes */ + if (cmt->info->model >= SH_CMT_48BIT) + cmt->reg_delay = DIV_ROUND_UP(2UL * USEC_PER_SEC, rate); + cmt->rate = rate / (cmt->info->width == 16 ? 512 : 8); /* Map the memory resource(s). */ ret = sh_cmt_map_memory(cmt); |