linux_dsm_epyc7002/arch/arm/plat-omap/include/plat/dmtimer.h

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/*
* arch/arm/plat-omap/include/plat/dmtimer.h
*
* OMAP Dual-Mode Timers
*
* Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com/
* Tarun Kanti DebBarma <tarun.kanti@ti.com>
* Thara Gopinath <thara@ti.com>
*
* Platform device conversion and hwmod support.
*
* Copyright (C) 2005 Nokia Corporation
* Author: Lauri Leukkunen <lauri.leukkunen@nokia.com>
* PWM and clock framwork support by Timo Teras.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
* NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/platform_device.h>
#ifndef __ASM_ARCH_DMTIMER_H
#define __ASM_ARCH_DMTIMER_H
/* clock sources */
#define OMAP_TIMER_SRC_SYS_CLK 0x00
#define OMAP_TIMER_SRC_32_KHZ 0x01
#define OMAP_TIMER_SRC_EXT_CLK 0x02
/* timer interrupt enable bits */
#define OMAP_TIMER_INT_CAPTURE (1 << 2)
#define OMAP_TIMER_INT_OVERFLOW (1 << 1)
#define OMAP_TIMER_INT_MATCH (1 << 0)
/* trigger types */
#define OMAP_TIMER_TRIGGER_NONE 0x00
#define OMAP_TIMER_TRIGGER_OVERFLOW 0x01
#define OMAP_TIMER_TRIGGER_OVERFLOW_AND_COMPARE 0x02
/* posted mode types */
#define OMAP_TIMER_NONPOSTED 0x00
#define OMAP_TIMER_POSTED 0x01
/* timer capabilities used in hwmod database */
#define OMAP_TIMER_SECURE 0x80000000
#define OMAP_TIMER_ALWON 0x40000000
#define OMAP_TIMER_HAS_PWM 0x20000000
#define OMAP_TIMER_NEEDS_RESET 0x10000000
#define OMAP_TIMER_HAS_DSP_IRQ 0x08000000
ARM: OMAP3+: Implement timer workaround for errata i103 and i767 Errata Titles: i103: Delay needed to read some GP timer, WD timer and sync timer registers after wakeup (OMAP3/4) i767: Delay needed to read some GP timer registers after wakeup (OMAP5) Description (i103/i767): If a General Purpose Timer (GPTimer) is in posted mode (TSICR [2].POSTED=1), due to internal resynchronizations, values read in TCRR, TCAR1 and TCAR2 registers right after the timer interface clock (L4) goes from stopped to active may not return the expected values. The most common event leading to this situation occurs upon wake up from idle. GPTimer non-posted synchronization mode is not impacted by this limitation. Workarounds: 1). Disable posted mode 2). Use static dependency between timer clock domain and MPUSS clock domain 3). Use no-idle mode when the timer is active Workarounds #2 and #3 are not pratical from a power standpoint and so workaround #1 has been implemented. Disabling posted mode adds some CPU overhead for configuring and reading the timers as the CPU has to wait for accesses to be re-synchronised within the timer. However, disabling posted mode guarantees correct operation. Please note that it is safe to use posted mode for timers if the counter (TCRR) and capture (TCARx) registers will never be read. An example of this is the clock-event system timer. This is used by the kernel to schedule events however, the timers counter is never read and capture registers are not used. Given that the kernel configures this timer often yet never reads the counter register it is safe to enable posted mode in this case. Hence, for the timer used for kernel clock-events, posted mode is enabled by overriding the errata for devices that are impacted by this defect. For drivers using the timers that do not read the counter or capture registers and wish to use posted mode, can override the errata and enable posted mode by making the following function calls. __omap_dm_timer_override_errata(timer, OMAP_TIMER_ERRATA_I103_I767); __omap_dm_timer_enable_posted(timer); Both dmtimers and watchdogs are impacted by this defect this patch only implements the workaround for the dmtimer. Currently the watchdog driver does not read the counter register and so no workaround is necessary. Posted mode will be disabled for all OMAP2+ devices (including AM33xx) using a GP timer as a clock-source timer to guarantee correct operation. This is not necessary for OMAP24xx devices but the default clock-source timer for OMAP24xx devices is the 32k-sync timer and not the GP timer and so should not have any impact. This should be re-visited for future devices if this errata is fixed. Confirmed with Vaibhav Hiremath that this bug also impacts AM33xx devices. Signed-off-by: Jon Hunter <jon-hunter@ti.com> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
2012-09-28 00:47:43 +07:00
/*
* timer errata flags
*
* Errata i103/i767 impacts all OMAP3/4/5 devices including AM33xx. This
* errata prevents us from using posted mode on these devices, unless the
* timer counter register is never read. For more details please refer to
* the OMAP3/4/5 errata documents.
*/
#define OMAP_TIMER_ERRATA_I103_I767 0x80000000
struct timer_regs {
u32 tidr;
u32 tier;
u32 twer;
u32 tclr;
u32 tcrr;
u32 tldr;
u32 ttrg;
u32 twps;
u32 tmar;
u32 tcar1;
u32 tsicr;
u32 tcar2;
u32 tpir;
u32 tnir;
u32 tcvr;
u32 tocr;
u32 towr;
};
struct omap_dm_timer {
int id;
int irq;
struct clk *fclk;
void __iomem *io_base;
void __iomem *irq_stat; /* TISR/IRQSTATUS interrupt status */
void __iomem *irq_ena; /* irq enable */
void __iomem *irq_dis; /* irq disable, only on v2 ip */
void __iomem *pend; /* write pending */
void __iomem *func_base; /* function register base */
unsigned long rate;
unsigned reserved:1;
unsigned posted:1;
struct timer_regs context;
int (*get_context_loss_count)(struct device *);
int ctx_loss_count;
int revision;
u32 capability;
u32 errata;
struct platform_device *pdev;
struct list_head node;
};
ARM: OMAP2+: Add dmtimer platform function to reserve systimers During early boot, one or two dmtimers are reserved by the kernel as system timers (for clocksource and clockevents). These timers are marked as reserved and the dmtimer driver is notified which timers have been reserved via the platform data information. For OMAP2+ devices the timers reserved may vary depending on device and compile flags. Therefore, it is not easy to assume which timers we be reserved for the system timers. In order to migrate the dmtimer driver to support device-tree we need a way to pass the timers reserved for system timers to the dmtimer driver. Using the platform data structure will not work in the same way as it is currently used because the platform data structure will be stored statically in the dmtimer itself and the platform data will be selected via the device-tree match device function (of_match_device). There are a couple ways to workaround this. One option is to store the system timers reserved for the kernel in the device-tree and query them on boot. The downside of this approach is that it adds some delay to parse the DT blob to search for the system timers. Secondly, for OMAP3 devices we have a dependency on compile time flags and the device-tree would not be aware of that kernel compile flags and so we would need to address that. The second option is to add a function to the dmtimer code to reserved the system timers during boot and so the dmtimer knows exactly which timers are being used for system timers. This also allows us to remove the "reserved" member from the timer platform data. This seemed like the simpler approach and so was implemented here. Signed-off-by: Jon Hunter <jon-hunter@ti.com> Signed-off-by: Tony Lindgren <tony@atomide.com>
2012-06-06 00:34:51 +07:00
int omap_dm_timer_reserve_systimer(int id);
struct omap_dm_timer *omap_dm_timer_request(void);
struct omap_dm_timer *omap_dm_timer_request_specific(int timer_id);
struct omap_dm_timer *omap_dm_timer_request_by_cap(u32 cap);
struct omap_dm_timer *omap_dm_timer_request_by_node(struct device_node *np);
int omap_dm_timer_free(struct omap_dm_timer *timer);
void omap_dm_timer_enable(struct omap_dm_timer *timer);
void omap_dm_timer_disable(struct omap_dm_timer *timer);
int omap_dm_timer_get_irq(struct omap_dm_timer *timer);
u32 omap_dm_timer_modify_idlect_mask(u32 inputmask);
struct clk *omap_dm_timer_get_fclk(struct omap_dm_timer *timer);
int omap_dm_timer_trigger(struct omap_dm_timer *timer);
int omap_dm_timer_start(struct omap_dm_timer *timer);
int omap_dm_timer_stop(struct omap_dm_timer *timer);
int omap_dm_timer_set_source(struct omap_dm_timer *timer, int source);
int omap_dm_timer_set_load(struct omap_dm_timer *timer, int autoreload, unsigned int value);
int omap_dm_timer_set_load_start(struct omap_dm_timer *timer, int autoreload, unsigned int value);
int omap_dm_timer_set_match(struct omap_dm_timer *timer, int enable, unsigned int match);
int omap_dm_timer_set_pwm(struct omap_dm_timer *timer, int def_on, int toggle, int trigger);
int omap_dm_timer_set_prescaler(struct omap_dm_timer *timer, int prescaler);
int omap_dm_timer_set_int_enable(struct omap_dm_timer *timer, unsigned int value);
int omap_dm_timer_set_int_disable(struct omap_dm_timer *timer, u32 mask);
unsigned int omap_dm_timer_read_status(struct omap_dm_timer *timer);
int omap_dm_timer_write_status(struct omap_dm_timer *timer, unsigned int value);
unsigned int omap_dm_timer_read_counter(struct omap_dm_timer *timer);
int omap_dm_timer_write_counter(struct omap_dm_timer *timer, unsigned int value);
int omap_dm_timers_active(void);
/*
* Do not use the defines below, they are not needed. They should be only
* used by dmtimer.c and sys_timer related code.
*/
/*
* The interrupt registers are different between v1 and v2 ip.
* These registers are offsets from timer->iobase.
*/
#define OMAP_TIMER_ID_OFFSET 0x00
#define OMAP_TIMER_OCP_CFG_OFFSET 0x10
#define OMAP_TIMER_V1_SYS_STAT_OFFSET 0x14
#define OMAP_TIMER_V1_STAT_OFFSET 0x18
#define OMAP_TIMER_V1_INT_EN_OFFSET 0x1c
#define OMAP_TIMER_V2_IRQSTATUS_RAW 0x24
#define OMAP_TIMER_V2_IRQSTATUS 0x28
#define OMAP_TIMER_V2_IRQENABLE_SET 0x2c
#define OMAP_TIMER_V2_IRQENABLE_CLR 0x30
/*
* The functional registers have a different base on v1 and v2 ip.
* These registers are offsets from timer->func_base. The func_base
* is samae as io_base for v1 and io_base + 0x14 for v2 ip.
*
*/
#define OMAP_TIMER_V2_FUNC_OFFSET 0x14
#define _OMAP_TIMER_WAKEUP_EN_OFFSET 0x20
#define _OMAP_TIMER_CTRL_OFFSET 0x24
#define OMAP_TIMER_CTRL_GPOCFG (1 << 14)
#define OMAP_TIMER_CTRL_CAPTMODE (1 << 13)
#define OMAP_TIMER_CTRL_PT (1 << 12)
#define OMAP_TIMER_CTRL_TCM_LOWTOHIGH (0x1 << 8)
#define OMAP_TIMER_CTRL_TCM_HIGHTOLOW (0x2 << 8)
#define OMAP_TIMER_CTRL_TCM_BOTHEDGES (0x3 << 8)
#define OMAP_TIMER_CTRL_SCPWM (1 << 7)
#define OMAP_TIMER_CTRL_CE (1 << 6) /* compare enable */
#define OMAP_TIMER_CTRL_PRE (1 << 5) /* prescaler enable */
#define OMAP_TIMER_CTRL_PTV_SHIFT 2 /* prescaler value shift */
#define OMAP_TIMER_CTRL_POSTED (1 << 2)
#define OMAP_TIMER_CTRL_AR (1 << 1) /* auto-reload enable */
#define OMAP_TIMER_CTRL_ST (1 << 0) /* start timer */
#define _OMAP_TIMER_COUNTER_OFFSET 0x28
#define _OMAP_TIMER_LOAD_OFFSET 0x2c
#define _OMAP_TIMER_TRIGGER_OFFSET 0x30
#define _OMAP_TIMER_WRITE_PEND_OFFSET 0x34
#define WP_NONE 0 /* no write pending bit */
#define WP_TCLR (1 << 0)
#define WP_TCRR (1 << 1)
#define WP_TLDR (1 << 2)
#define WP_TTGR (1 << 3)
#define WP_TMAR (1 << 4)
#define WP_TPIR (1 << 5)
#define WP_TNIR (1 << 6)
#define WP_TCVR (1 << 7)
#define WP_TOCR (1 << 8)
#define WP_TOWR (1 << 9)
#define _OMAP_TIMER_MATCH_OFFSET 0x38
#define _OMAP_TIMER_CAPTURE_OFFSET 0x3c
#define _OMAP_TIMER_IF_CTRL_OFFSET 0x40
#define _OMAP_TIMER_CAPTURE2_OFFSET 0x44 /* TCAR2, 34xx only */
#define _OMAP_TIMER_TICK_POS_OFFSET 0x48 /* TPIR, 34xx only */
#define _OMAP_TIMER_TICK_NEG_OFFSET 0x4c /* TNIR, 34xx only */
#define _OMAP_TIMER_TICK_COUNT_OFFSET 0x50 /* TCVR, 34xx only */
#define _OMAP_TIMER_TICK_INT_MASK_SET_OFFSET 0x54 /* TOCR, 34xx only */
#define _OMAP_TIMER_TICK_INT_MASK_COUNT_OFFSET 0x58 /* TOWR, 34xx only */
/* register offsets with the write pending bit encoded */
#define WPSHIFT 16
#define OMAP_TIMER_WAKEUP_EN_REG (_OMAP_TIMER_WAKEUP_EN_OFFSET \
| (WP_NONE << WPSHIFT))
#define OMAP_TIMER_CTRL_REG (_OMAP_TIMER_CTRL_OFFSET \
| (WP_TCLR << WPSHIFT))
#define OMAP_TIMER_COUNTER_REG (_OMAP_TIMER_COUNTER_OFFSET \
| (WP_TCRR << WPSHIFT))
#define OMAP_TIMER_LOAD_REG (_OMAP_TIMER_LOAD_OFFSET \
| (WP_TLDR << WPSHIFT))
#define OMAP_TIMER_TRIGGER_REG (_OMAP_TIMER_TRIGGER_OFFSET \
| (WP_TTGR << WPSHIFT))
#define OMAP_TIMER_WRITE_PEND_REG (_OMAP_TIMER_WRITE_PEND_OFFSET \
| (WP_NONE << WPSHIFT))
#define OMAP_TIMER_MATCH_REG (_OMAP_TIMER_MATCH_OFFSET \
| (WP_TMAR << WPSHIFT))
#define OMAP_TIMER_CAPTURE_REG (_OMAP_TIMER_CAPTURE_OFFSET \
| (WP_NONE << WPSHIFT))
#define OMAP_TIMER_IF_CTRL_REG (_OMAP_TIMER_IF_CTRL_OFFSET \
| (WP_NONE << WPSHIFT))
#define OMAP_TIMER_CAPTURE2_REG (_OMAP_TIMER_CAPTURE2_OFFSET \
| (WP_NONE << WPSHIFT))
#define OMAP_TIMER_TICK_POS_REG (_OMAP_TIMER_TICK_POS_OFFSET \
| (WP_TPIR << WPSHIFT))
#define OMAP_TIMER_TICK_NEG_REG (_OMAP_TIMER_TICK_NEG_OFFSET \
| (WP_TNIR << WPSHIFT))
#define OMAP_TIMER_TICK_COUNT_REG (_OMAP_TIMER_TICK_COUNT_OFFSET \
| (WP_TCVR << WPSHIFT))
#define OMAP_TIMER_TICK_INT_MASK_SET_REG \
(_OMAP_TIMER_TICK_INT_MASK_SET_OFFSET | (WP_TOCR << WPSHIFT))
#define OMAP_TIMER_TICK_INT_MASK_COUNT_REG \
(_OMAP_TIMER_TICK_INT_MASK_COUNT_OFFSET | (WP_TOWR << WPSHIFT))
static inline u32 __omap_dm_timer_read(struct omap_dm_timer *timer, u32 reg,
int posted)
{
if (posted)
while (readl_relaxed(timer->pend) & (reg >> WPSHIFT))
cpu_relax();
return readl_relaxed(timer->func_base + (reg & 0xff));
}
static inline void __omap_dm_timer_write(struct omap_dm_timer *timer,
u32 reg, u32 val, int posted)
{
if (posted)
while (readl_relaxed(timer->pend) & (reg >> WPSHIFT))
cpu_relax();
writel_relaxed(val, timer->func_base + (reg & 0xff));
}
static inline void __omap_dm_timer_init_regs(struct omap_dm_timer *timer)
{
u32 tidr;
/* Assume v1 ip if bits [31:16] are zero */
tidr = readl_relaxed(timer->io_base);
if (!(tidr >> 16)) {
timer->revision = 1;
timer->irq_stat = timer->io_base + OMAP_TIMER_V1_STAT_OFFSET;
timer->irq_ena = timer->io_base + OMAP_TIMER_V1_INT_EN_OFFSET;
timer->irq_dis = timer->io_base + OMAP_TIMER_V1_INT_EN_OFFSET;
timer->pend = timer->io_base + _OMAP_TIMER_WRITE_PEND_OFFSET;
timer->func_base = timer->io_base;
} else {
timer->revision = 2;
timer->irq_stat = timer->io_base + OMAP_TIMER_V2_IRQSTATUS;
timer->irq_ena = timer->io_base + OMAP_TIMER_V2_IRQENABLE_SET;
timer->irq_dis = timer->io_base + OMAP_TIMER_V2_IRQENABLE_CLR;
timer->pend = timer->io_base +
_OMAP_TIMER_WRITE_PEND_OFFSET +
OMAP_TIMER_V2_FUNC_OFFSET;
timer->func_base = timer->io_base + OMAP_TIMER_V2_FUNC_OFFSET;
}
}
ARM: OMAP3+: Implement timer workaround for errata i103 and i767 Errata Titles: i103: Delay needed to read some GP timer, WD timer and sync timer registers after wakeup (OMAP3/4) i767: Delay needed to read some GP timer registers after wakeup (OMAP5) Description (i103/i767): If a General Purpose Timer (GPTimer) is in posted mode (TSICR [2].POSTED=1), due to internal resynchronizations, values read in TCRR, TCAR1 and TCAR2 registers right after the timer interface clock (L4) goes from stopped to active may not return the expected values. The most common event leading to this situation occurs upon wake up from idle. GPTimer non-posted synchronization mode is not impacted by this limitation. Workarounds: 1). Disable posted mode 2). Use static dependency between timer clock domain and MPUSS clock domain 3). Use no-idle mode when the timer is active Workarounds #2 and #3 are not pratical from a power standpoint and so workaround #1 has been implemented. Disabling posted mode adds some CPU overhead for configuring and reading the timers as the CPU has to wait for accesses to be re-synchronised within the timer. However, disabling posted mode guarantees correct operation. Please note that it is safe to use posted mode for timers if the counter (TCRR) and capture (TCARx) registers will never be read. An example of this is the clock-event system timer. This is used by the kernel to schedule events however, the timers counter is never read and capture registers are not used. Given that the kernel configures this timer often yet never reads the counter register it is safe to enable posted mode in this case. Hence, for the timer used for kernel clock-events, posted mode is enabled by overriding the errata for devices that are impacted by this defect. For drivers using the timers that do not read the counter or capture registers and wish to use posted mode, can override the errata and enable posted mode by making the following function calls. __omap_dm_timer_override_errata(timer, OMAP_TIMER_ERRATA_I103_I767); __omap_dm_timer_enable_posted(timer); Both dmtimers and watchdogs are impacted by this defect this patch only implements the workaround for the dmtimer. Currently the watchdog driver does not read the counter register and so no workaround is necessary. Posted mode will be disabled for all OMAP2+ devices (including AM33xx) using a GP timer as a clock-source timer to guarantee correct operation. This is not necessary for OMAP24xx devices but the default clock-source timer for OMAP24xx devices is the 32k-sync timer and not the GP timer and so should not have any impact. This should be re-visited for future devices if this errata is fixed. Confirmed with Vaibhav Hiremath that this bug also impacts AM33xx devices. Signed-off-by: Jon Hunter <jon-hunter@ti.com> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
2012-09-28 00:47:43 +07:00
/*
* __omap_dm_timer_enable_posted - enables write posted mode
* @timer: pointer to timer instance handle
*
* Enables the write posted mode for the timer. When posted mode is enabled
* writes to certain timer registers are immediately acknowledged by the
* internal bus and hence prevents stalling the CPU waiting for the write to
* complete. Enabling this feature can improve performance for writing to the
* timer registers.
*/
static inline void __omap_dm_timer_enable_posted(struct omap_dm_timer *timer)
{
if (timer->posted)
return;
if (timer->errata & OMAP_TIMER_ERRATA_I103_I767) {
timer->posted = OMAP_TIMER_NONPOSTED;
__omap_dm_timer_write(timer, OMAP_TIMER_IF_CTRL_REG, 0, 0);
ARM: OMAP3+: Implement timer workaround for errata i103 and i767 Errata Titles: i103: Delay needed to read some GP timer, WD timer and sync timer registers after wakeup (OMAP3/4) i767: Delay needed to read some GP timer registers after wakeup (OMAP5) Description (i103/i767): If a General Purpose Timer (GPTimer) is in posted mode (TSICR [2].POSTED=1), due to internal resynchronizations, values read in TCRR, TCAR1 and TCAR2 registers right after the timer interface clock (L4) goes from stopped to active may not return the expected values. The most common event leading to this situation occurs upon wake up from idle. GPTimer non-posted synchronization mode is not impacted by this limitation. Workarounds: 1). Disable posted mode 2). Use static dependency between timer clock domain and MPUSS clock domain 3). Use no-idle mode when the timer is active Workarounds #2 and #3 are not pratical from a power standpoint and so workaround #1 has been implemented. Disabling posted mode adds some CPU overhead for configuring and reading the timers as the CPU has to wait for accesses to be re-synchronised within the timer. However, disabling posted mode guarantees correct operation. Please note that it is safe to use posted mode for timers if the counter (TCRR) and capture (TCARx) registers will never be read. An example of this is the clock-event system timer. This is used by the kernel to schedule events however, the timers counter is never read and capture registers are not used. Given that the kernel configures this timer often yet never reads the counter register it is safe to enable posted mode in this case. Hence, for the timer used for kernel clock-events, posted mode is enabled by overriding the errata for devices that are impacted by this defect. For drivers using the timers that do not read the counter or capture registers and wish to use posted mode, can override the errata and enable posted mode by making the following function calls. __omap_dm_timer_override_errata(timer, OMAP_TIMER_ERRATA_I103_I767); __omap_dm_timer_enable_posted(timer); Both dmtimers and watchdogs are impacted by this defect this patch only implements the workaround for the dmtimer. Currently the watchdog driver does not read the counter register and so no workaround is necessary. Posted mode will be disabled for all OMAP2+ devices (including AM33xx) using a GP timer as a clock-source timer to guarantee correct operation. This is not necessary for OMAP24xx devices but the default clock-source timer for OMAP24xx devices is the 32k-sync timer and not the GP timer and so should not have any impact. This should be re-visited for future devices if this errata is fixed. Confirmed with Vaibhav Hiremath that this bug also impacts AM33xx devices. Signed-off-by: Jon Hunter <jon-hunter@ti.com> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
2012-09-28 00:47:43 +07:00
return;
}
__omap_dm_timer_write(timer, OMAP_TIMER_IF_CTRL_REG,
ARM: OMAP3+: Implement timer workaround for errata i103 and i767 Errata Titles: i103: Delay needed to read some GP timer, WD timer and sync timer registers after wakeup (OMAP3/4) i767: Delay needed to read some GP timer registers after wakeup (OMAP5) Description (i103/i767): If a General Purpose Timer (GPTimer) is in posted mode (TSICR [2].POSTED=1), due to internal resynchronizations, values read in TCRR, TCAR1 and TCAR2 registers right after the timer interface clock (L4) goes from stopped to active may not return the expected values. The most common event leading to this situation occurs upon wake up from idle. GPTimer non-posted synchronization mode is not impacted by this limitation. Workarounds: 1). Disable posted mode 2). Use static dependency between timer clock domain and MPUSS clock domain 3). Use no-idle mode when the timer is active Workarounds #2 and #3 are not pratical from a power standpoint and so workaround #1 has been implemented. Disabling posted mode adds some CPU overhead for configuring and reading the timers as the CPU has to wait for accesses to be re-synchronised within the timer. However, disabling posted mode guarantees correct operation. Please note that it is safe to use posted mode for timers if the counter (TCRR) and capture (TCARx) registers will never be read. An example of this is the clock-event system timer. This is used by the kernel to schedule events however, the timers counter is never read and capture registers are not used. Given that the kernel configures this timer often yet never reads the counter register it is safe to enable posted mode in this case. Hence, for the timer used for kernel clock-events, posted mode is enabled by overriding the errata for devices that are impacted by this defect. For drivers using the timers that do not read the counter or capture registers and wish to use posted mode, can override the errata and enable posted mode by making the following function calls. __omap_dm_timer_override_errata(timer, OMAP_TIMER_ERRATA_I103_I767); __omap_dm_timer_enable_posted(timer); Both dmtimers and watchdogs are impacted by this defect this patch only implements the workaround for the dmtimer. Currently the watchdog driver does not read the counter register and so no workaround is necessary. Posted mode will be disabled for all OMAP2+ devices (including AM33xx) using a GP timer as a clock-source timer to guarantee correct operation. This is not necessary for OMAP24xx devices but the default clock-source timer for OMAP24xx devices is the 32k-sync timer and not the GP timer and so should not have any impact. This should be re-visited for future devices if this errata is fixed. Confirmed with Vaibhav Hiremath that this bug also impacts AM33xx devices. Signed-off-by: Jon Hunter <jon-hunter@ti.com> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
2012-09-28 00:47:43 +07:00
OMAP_TIMER_CTRL_POSTED, 0);
timer->context.tsicr = OMAP_TIMER_CTRL_POSTED;
timer->posted = OMAP_TIMER_POSTED;
}
/**
* __omap_dm_timer_override_errata - override errata flags for a timer
* @timer: pointer to timer handle
* @errata: errata flags to be ignored
*
* For a given timer, override a timer errata by clearing the flags
* specified by the errata argument. A specific erratum should only be
* overridden for a timer if the timer is used in such a way the erratum
* has no impact.
*/
static inline void __omap_dm_timer_override_errata(struct omap_dm_timer *timer,
u32 errata)
{
timer->errata &= ~errata;
}
static inline void __omap_dm_timer_stop(struct omap_dm_timer *timer,
int posted, unsigned long rate)
{
u32 l;
l = __omap_dm_timer_read(timer, OMAP_TIMER_CTRL_REG, posted);
if (l & OMAP_TIMER_CTRL_ST) {
l &= ~0x1;
__omap_dm_timer_write(timer, OMAP_TIMER_CTRL_REG, l, posted);
#ifdef CONFIG_ARCH_OMAP2PLUS
/* Readback to make sure write has completed */
__omap_dm_timer_read(timer, OMAP_TIMER_CTRL_REG, posted);
/*
* Wait for functional clock period x 3.5 to make sure that
* timer is stopped
*/
udelay(3500000 / rate + 1);
#endif
}
/* Ack possibly pending interrupt */
writel_relaxed(OMAP_TIMER_INT_OVERFLOW, timer->irq_stat);
}
static inline void __omap_dm_timer_load_start(struct omap_dm_timer *timer,
u32 ctrl, unsigned int load,
int posted)
{
__omap_dm_timer_write(timer, OMAP_TIMER_COUNTER_REG, load, posted);
__omap_dm_timer_write(timer, OMAP_TIMER_CTRL_REG, ctrl, posted);
}
static inline void __omap_dm_timer_int_enable(struct omap_dm_timer *timer,
unsigned int value)
{
writel_relaxed(value, timer->irq_ena);
__omap_dm_timer_write(timer, OMAP_TIMER_WAKEUP_EN_REG, value, 0);
}
static inline unsigned int
__omap_dm_timer_read_counter(struct omap_dm_timer *timer, int posted)
{
return __omap_dm_timer_read(timer, OMAP_TIMER_COUNTER_REG, posted);
}
static inline void __omap_dm_timer_write_status(struct omap_dm_timer *timer,
unsigned int value)
{
writel_relaxed(value, timer->irq_stat);
}
#endif /* __ASM_ARCH_DMTIMER_H */