![Jisheng Zhang](/assets/img/avatar_default.png)
Let's assume the counter value is 0xf0000000, the pistachio clocksource read cycles function should return ~0x0fffffff but actually it returns 0xffffffff0fffffff. That occurs because: ~(cycle_t)value is different from (cycle_t)~value. unsigned long val = ~(unsigned long)0xf0000000; 40049a: 48 b8 ff ff ff 0f ff movabs $0xffffffff0fffffff,%rax unsigned long val = (unsigned long)~0xf0000000; 40049a: 48 c7 45 f8 ff ff ff movq $0xfffffff,-0x8(%rbp) We fix this issue by calculating bitwise-not counter, then cast to cycle_t. Signed-off-by: Jisheng Zhang <jszhang@marvell.com> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
219 lines
5.5 KiB
C
219 lines
5.5 KiB
C
/*
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* Pistachio clocksource based on general-purpose timers
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*
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* Copyright (C) 2015 Imagination Technologies
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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#define pr_fmt(fmt) "%s: " fmt, __func__
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#include <linux/clk.h>
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#include <linux/clocksource.h>
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#include <linux/clockchips.h>
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#include <linux/delay.h>
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#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/spinlock.h>
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#include <linux/mfd/syscon.h>
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#include <linux/of.h>
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#include <linux/of_address.h>
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#include <linux/platform_device.h>
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#include <linux/regmap.h>
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#include <linux/sched_clock.h>
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#include <linux/time.h>
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/* Top level reg */
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#define CR_TIMER_CTRL_CFG 0x00
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#define TIMER_ME_GLOBAL BIT(0)
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#define CR_TIMER_REV 0x10
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/* Timer specific registers */
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#define TIMER_CFG 0x20
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#define TIMER_ME_LOCAL BIT(0)
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#define TIMER_RELOAD_VALUE 0x24
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#define TIMER_CURRENT_VALUE 0x28
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#define TIMER_CURRENT_OVERFLOW_VALUE 0x2C
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#define TIMER_IRQ_STATUS 0x30
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#define TIMER_IRQ_CLEAR 0x34
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#define TIMER_IRQ_MASK 0x38
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#define PERIP_TIMER_CONTROL 0x90
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/* Timer specific configuration Values */
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#define RELOAD_VALUE 0xffffffff
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struct pistachio_clocksource {
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void __iomem *base;
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raw_spinlock_t lock;
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struct clocksource cs;
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};
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static struct pistachio_clocksource pcs_gpt;
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#define to_pistachio_clocksource(cs) \
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container_of(cs, struct pistachio_clocksource, cs)
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static inline u32 gpt_readl(void __iomem *base, u32 offset, u32 gpt_id)
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{
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return readl(base + 0x20 * gpt_id + offset);
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}
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static inline void gpt_writel(void __iomem *base, u32 value, u32 offset,
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u32 gpt_id)
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{
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writel(value, base + 0x20 * gpt_id + offset);
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}
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static cycle_t notrace
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pistachio_clocksource_read_cycles(struct clocksource *cs)
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{
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struct pistachio_clocksource *pcs = to_pistachio_clocksource(cs);
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u32 counter, overflw;
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unsigned long flags;
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/*
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* The counter value is only refreshed after the overflow value is read.
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* And they must be read in strict order, hence raw spin lock added.
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*/
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raw_spin_lock_irqsave(&pcs->lock, flags);
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overflw = gpt_readl(pcs->base, TIMER_CURRENT_OVERFLOW_VALUE, 0);
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counter = gpt_readl(pcs->base, TIMER_CURRENT_VALUE, 0);
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raw_spin_unlock_irqrestore(&pcs->lock, flags);
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return (cycle_t)~counter;
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}
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static u64 notrace pistachio_read_sched_clock(void)
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{
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return pistachio_clocksource_read_cycles(&pcs_gpt.cs);
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}
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static void pistachio_clksrc_set_mode(struct clocksource *cs, int timeridx,
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int enable)
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{
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struct pistachio_clocksource *pcs = to_pistachio_clocksource(cs);
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u32 val;
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val = gpt_readl(pcs->base, TIMER_CFG, timeridx);
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if (enable)
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val |= TIMER_ME_LOCAL;
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else
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val &= ~TIMER_ME_LOCAL;
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gpt_writel(pcs->base, val, TIMER_CFG, timeridx);
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}
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static void pistachio_clksrc_enable(struct clocksource *cs, int timeridx)
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{
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struct pistachio_clocksource *pcs = to_pistachio_clocksource(cs);
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/* Disable GPT local before loading reload value */
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pistachio_clksrc_set_mode(cs, timeridx, false);
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gpt_writel(pcs->base, RELOAD_VALUE, TIMER_RELOAD_VALUE, timeridx);
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pistachio_clksrc_set_mode(cs, timeridx, true);
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}
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static void pistachio_clksrc_disable(struct clocksource *cs, int timeridx)
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{
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/* Disable GPT local */
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pistachio_clksrc_set_mode(cs, timeridx, false);
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}
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static int pistachio_clocksource_enable(struct clocksource *cs)
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{
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pistachio_clksrc_enable(cs, 0);
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return 0;
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}
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static void pistachio_clocksource_disable(struct clocksource *cs)
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{
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pistachio_clksrc_disable(cs, 0);
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}
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/* Desirable clock source for pistachio platform */
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static struct pistachio_clocksource pcs_gpt = {
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.cs = {
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.name = "gptimer",
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.rating = 300,
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.enable = pistachio_clocksource_enable,
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.disable = pistachio_clocksource_disable,
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.read = pistachio_clocksource_read_cycles,
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.mask = CLOCKSOURCE_MASK(32),
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.flags = CLOCK_SOURCE_IS_CONTINUOUS |
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CLOCK_SOURCE_SUSPEND_NONSTOP,
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},
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};
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static void __init pistachio_clksrc_of_init(struct device_node *node)
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{
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struct clk *sys_clk, *fast_clk;
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struct regmap *periph_regs;
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unsigned long rate;
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int ret;
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pcs_gpt.base = of_iomap(node, 0);
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if (!pcs_gpt.base) {
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pr_err("cannot iomap\n");
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return;
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}
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periph_regs = syscon_regmap_lookup_by_phandle(node, "img,cr-periph");
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if (IS_ERR(periph_regs)) {
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pr_err("cannot get peripheral regmap (%lu)\n",
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PTR_ERR(periph_regs));
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return;
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}
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/* Switch to using the fast counter clock */
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ret = regmap_update_bits(periph_regs, PERIP_TIMER_CONTROL,
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0xf, 0x0);
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if (ret)
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return;
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sys_clk = of_clk_get_by_name(node, "sys");
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if (IS_ERR(sys_clk)) {
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pr_err("clock get failed (%lu)\n", PTR_ERR(sys_clk));
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return;
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}
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fast_clk = of_clk_get_by_name(node, "fast");
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if (IS_ERR(fast_clk)) {
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pr_err("clock get failed (%lu)\n", PTR_ERR(fast_clk));
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return;
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}
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ret = clk_prepare_enable(sys_clk);
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if (ret < 0) {
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pr_err("failed to enable clock (%d)\n", ret);
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return;
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}
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ret = clk_prepare_enable(fast_clk);
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if (ret < 0) {
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pr_err("failed to enable clock (%d)\n", ret);
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clk_disable_unprepare(sys_clk);
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return;
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}
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rate = clk_get_rate(fast_clk);
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/* Disable irq's for clocksource usage */
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gpt_writel(&pcs_gpt.base, 0, TIMER_IRQ_MASK, 0);
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gpt_writel(&pcs_gpt.base, 0, TIMER_IRQ_MASK, 1);
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gpt_writel(&pcs_gpt.base, 0, TIMER_IRQ_MASK, 2);
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gpt_writel(&pcs_gpt.base, 0, TIMER_IRQ_MASK, 3);
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/* Enable timer block */
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writel(TIMER_ME_GLOBAL, pcs_gpt.base);
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raw_spin_lock_init(&pcs_gpt.lock);
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sched_clock_register(pistachio_read_sched_clock, 32, rate);
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clocksource_register_hz(&pcs_gpt.cs, rate);
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}
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CLOCKSOURCE_OF_DECLARE(pistachio_gptimer, "img,pistachio-gptimer",
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pistachio_clksrc_of_init);
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