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* linux/arch/arm/mach-at91/clock.c
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* Copyright (C) 2005 David Brownell
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* Copyright (C) 2005 Ivan Kokshaysky
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/debugfs.h>
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#include <linux/seq_file.h>
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#include <linux/list.h>
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#include <linux/errno.h>
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#include <linux/err.h>
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#include <linux/spinlock.h>
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#include <linux/delay.h>
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#include <linux/clk.h>
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#include <mach/hardware.h>
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#include <mach/at91_pmc.h>
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* There's a lot more which can be done with clocks, including cpufreq
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* integration, slow clock mode support (for system suspend), letting
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* PLLB be used at other rates (on boards that don't need USB), etc.
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#define clk_is_primary(x) ((x)->type & CLK_TYPE_PRIMARY)
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#define clk_is_programmable(x) ((x)->type & CLK_TYPE_PROGRAMMABLE)
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#define clk_is_peripheral(x) ((x)->type & CLK_TYPE_PERIPHERAL)
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#define clk_is_sys(x) ((x)->type & CLK_TYPE_SYSTEM)
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* Chips have some kind of clocks : group them by functionality
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#define cpu_has_utmi() ( cpu_is_at91cap9() \
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|| cpu_is_at91sam9rl() \
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|| cpu_is_at91sam9g45())
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#define cpu_has_800M_plla() ( cpu_is_at91sam9g20() \
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|| cpu_is_at91sam9g45())
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#define cpu_has_300M_plla() (cpu_is_at91sam9g10())
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#define cpu_has_pllb() (!(cpu_is_at91sam9rl() \
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|| cpu_is_at91sam9g45()))
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#define cpu_has_upll() (cpu_is_at91sam9g45())
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/* USB host HS & FS */
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#define cpu_has_uhp() (!cpu_is_at91sam9rl())
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/* USB device FS only */
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#define cpu_has_udpfs() (!(cpu_is_at91sam9rl() \
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|| cpu_is_at91sam9g45()))
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static LIST_HEAD(clocks);
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static DEFINE_SPINLOCK(clk_lock);
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static u32 at91_pllb_usb_init;
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* Four primary clock sources: two crystal oscillators (32K, main), and
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* two PLLs. PLLA usually runs the master clock; and PLLB must run at
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* 48 MHz (unless no USB function clocks are needed). The main clock and
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* both PLLs are turned off to run in "slow clock mode" (system suspend).
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static struct clk clk32k = {
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.rate_hz = AT91_SLOW_CLOCK,
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.users = 1, /* always on */
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.type = CLK_TYPE_PRIMARY,
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static struct clk main_clk = {
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.pmc_mask = AT91_PMC_MOSCS, /* in PMC_SR */
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.type = CLK_TYPE_PRIMARY,
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static struct clk plla = {
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.pmc_mask = AT91_PMC_LOCKA, /* in PMC_SR */
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.type = CLK_TYPE_PRIMARY | CLK_TYPE_PLL,
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static void pllb_mode(struct clk *clk, int is_on)
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is_on = AT91_PMC_LOCKB;
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value = at91_pllb_usb_init;
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// REVISIT: Add work-around for AT91RM9200 Errata #26 ?
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at91_sys_write(AT91_CKGR_PLLBR, value);
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} while ((at91_sys_read(AT91_PMC_SR) & AT91_PMC_LOCKB) != is_on);
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static struct clk pllb = {
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.pmc_mask = AT91_PMC_LOCKB, /* in PMC_SR */
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.type = CLK_TYPE_PRIMARY | CLK_TYPE_PLL,
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static void pmc_sys_mode(struct clk *clk, int is_on)
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at91_sys_write(AT91_PMC_SCER, clk->pmc_mask);
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at91_sys_write(AT91_PMC_SCDR, clk->pmc_mask);
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static void pmc_uckr_mode(struct clk *clk, int is_on)
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unsigned int uckr = at91_sys_read(AT91_CKGR_UCKR);
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if (cpu_is_at91sam9g45()) {
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uckr |= AT91_PMC_BIASEN;
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uckr &= ~AT91_PMC_BIASEN;
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is_on = AT91_PMC_LOCKU;
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at91_sys_write(AT91_CKGR_UCKR, uckr | clk->pmc_mask);
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at91_sys_write(AT91_CKGR_UCKR, uckr & ~(clk->pmc_mask));
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} while ((at91_sys_read(AT91_PMC_SR) & AT91_PMC_LOCKU) != is_on);
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/* USB function clocks (PLLB must be 48 MHz) */
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static struct clk udpck = {
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.mode = pmc_sys_mode,
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struct clk utmi_clk = {
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.pmc_mask = AT91_PMC_UPLLEN, /* in CKGR_UCKR */
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.mode = pmc_uckr_mode,
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.type = CLK_TYPE_PLL,
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static struct clk uhpck = {
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/*.parent = ... we choose parent at runtime */
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.mode = pmc_sys_mode,
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* The master clock is divided from the CPU clock (by 1-4). It's used for
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* memory, interfaces to on-chip peripherals, the AIC, and sometimes more
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* (e.g baud rate generation). It's sourced from one of the primary clocks.
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.pmc_mask = AT91_PMC_MCKRDY, /* in PMC_SR */
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static void pmc_periph_mode(struct clk *clk, int is_on)
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at91_sys_write(AT91_PMC_PCER, clk->pmc_mask);
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at91_sys_write(AT91_PMC_PCDR, clk->pmc_mask);
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static struct clk __init *at91_css_to_clk(unsigned long css)
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case AT91_PMC_CSS_SLOW:
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case AT91_PMC_CSS_MAIN:
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case AT91_PMC_CSS_PLLA:
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case AT91_PMC_CSS_PLLB:
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/* CSS_PLLB == CSS_UPLL */
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else if (cpu_has_pllb())
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static void __clk_enable(struct clk *clk)
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__clk_enable(clk->parent);
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if (clk->users++ == 0 && clk->mode)
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int clk_enable(struct clk *clk)
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spin_lock_irqsave(&clk_lock, flags);
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spin_unlock_irqrestore(&clk_lock, flags);
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EXPORT_SYMBOL(clk_enable);
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static void __clk_disable(struct clk *clk)
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BUG_ON(clk->users == 0);
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if (--clk->users == 0 && clk->mode)
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__clk_disable(clk->parent);
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void clk_disable(struct clk *clk)
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spin_lock_irqsave(&clk_lock, flags);
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spin_unlock_irqrestore(&clk_lock, flags);
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EXPORT_SYMBOL(clk_disable);
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unsigned long clk_get_rate(struct clk *clk)
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spin_lock_irqsave(&clk_lock, flags);
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if (rate || !clk->parent)
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spin_unlock_irqrestore(&clk_lock, flags);
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EXPORT_SYMBOL(clk_get_rate);
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/*------------------------------------------------------------------------*/
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#ifdef CONFIG_AT91_PROGRAMMABLE_CLOCKS
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* For now, only the programmable clocks support reparenting (MCK could
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* do this too, with care) or rate changing (the PLLs could do this too,
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* ditto MCK but that's more for cpufreq). Drivers may reparent to get
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* a better rate match; we don't.
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long clk_round_rate(struct clk *clk, unsigned long rate)
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unsigned long actual;
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unsigned long prev = ULONG_MAX;
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if (!clk_is_programmable(clk))
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spin_lock_irqsave(&clk_lock, flags);
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actual = clk->parent->rate_hz;
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for (prescale = 0; prescale < 7; prescale++) {
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if (actual && actual <= rate) {
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if ((prev - rate) < (rate - actual)) {
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spin_unlock_irqrestore(&clk_lock, flags);
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return (prescale < 7) ? actual : -ENOENT;
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EXPORT_SYMBOL(clk_round_rate);
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int clk_set_rate(struct clk *clk, unsigned long rate)
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unsigned long actual;
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if (!clk_is_programmable(clk))
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spin_lock_irqsave(&clk_lock, flags);
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actual = clk->parent->rate_hz;
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for (prescale = 0; prescale < 7; prescale++) {
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if (actual && actual <= rate) {
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pckr = at91_sys_read(AT91_PMC_PCKR(clk->id));
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pckr &= AT91_PMC_CSS; /* clock selection */
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pckr |= prescale << 2;
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at91_sys_write(AT91_PMC_PCKR(clk->id), pckr);
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clk->rate_hz = actual;
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spin_unlock_irqrestore(&clk_lock, flags);
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return (prescale < 7) ? actual : -ENOENT;
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EXPORT_SYMBOL(clk_set_rate);
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struct clk *clk_get_parent(struct clk *clk)
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EXPORT_SYMBOL(clk_get_parent);
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int clk_set_parent(struct clk *clk, struct clk *parent)
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if (!clk_is_primary(parent) || !clk_is_programmable(clk))
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if (cpu_is_at91sam9rl() && parent->id == AT91_PMC_CSS_PLLB)
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spin_lock_irqsave(&clk_lock, flags);
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clk->rate_hz = parent->rate_hz;
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clk->parent = parent;
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at91_sys_write(AT91_PMC_PCKR(clk->id), parent->id);
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spin_unlock_irqrestore(&clk_lock, flags);
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EXPORT_SYMBOL(clk_set_parent);
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/* establish PCK0..PCKN parentage and rate */
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static void __init init_programmable_clock(struct clk *clk)
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pckr = at91_sys_read(AT91_PMC_PCKR(clk->id));
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parent = at91_css_to_clk(pckr & AT91_PMC_CSS);
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clk->parent = parent;
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clk->rate_hz = parent->rate_hz / (1 << ((pckr & AT91_PMC_PRES) >> 2));
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#endif /* CONFIG_AT91_PROGRAMMABLE_CLOCKS */
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/*------------------------------------------------------------------------*/
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#ifdef CONFIG_DEBUG_FS
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static int at91_clk_show(struct seq_file *s, void *unused)
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u32 scsr, pcsr, uckr = 0, sr;
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seq_printf(s, "SCSR = %8x\n", scsr = at91_sys_read(AT91_PMC_SCSR));
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seq_printf(s, "PCSR = %8x\n", pcsr = at91_sys_read(AT91_PMC_PCSR));
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seq_printf(s, "MOR = %8x\n", at91_sys_read(AT91_CKGR_MOR));
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seq_printf(s, "MCFR = %8x\n", at91_sys_read(AT91_CKGR_MCFR));
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seq_printf(s, "PLLA = %8x\n", at91_sys_read(AT91_CKGR_PLLAR));
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seq_printf(s, "PLLB = %8x\n", at91_sys_read(AT91_CKGR_PLLBR));
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seq_printf(s, "UCKR = %8x\n", uckr = at91_sys_read(AT91_CKGR_UCKR));
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seq_printf(s, "MCKR = %8x\n", at91_sys_read(AT91_PMC_MCKR));
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seq_printf(s, "USB = %8x\n", at91_sys_read(AT91_PMC_USB));
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seq_printf(s, "SR = %8x\n", sr = at91_sys_read(AT91_PMC_SR));
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list_for_each_entry(clk, &clocks, node) {
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if (clk->mode == pmc_sys_mode)
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state = (scsr & clk->pmc_mask) ? "on" : "off";
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else if (clk->mode == pmc_periph_mode)
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state = (pcsr & clk->pmc_mask) ? "on" : "off";
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else if (clk->mode == pmc_uckr_mode)
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state = (uckr & clk->pmc_mask) ? "on" : "off";
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else if (clk->pmc_mask)
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state = (sr & clk->pmc_mask) ? "on" : "off";
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else if (clk == &clk32k || clk == &main_clk)
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seq_printf(s, "%-10s users=%2d %-3s %9ld Hz %s\n",
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clk->name, clk->users, state, clk_get_rate(clk),
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clk->parent ? clk->parent->name : "");
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static int at91_clk_open(struct inode *inode, struct file *file)
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return single_open(file, at91_clk_show, NULL);
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static const struct file_operations at91_clk_operations = {
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.open = at91_clk_open,
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.release = single_release,
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static int __init at91_clk_debugfs_init(void)
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/* /sys/kernel/debug/at91_clk */
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(void) debugfs_create_file("at91_clk", S_IFREG | S_IRUGO, NULL, NULL, &at91_clk_operations);
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postcore_initcall(at91_clk_debugfs_init);
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/*------------------------------------------------------------------------*/
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/* Register a new clock */
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static void __init at91_clk_add(struct clk *clk)
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list_add_tail(&clk->node, &clocks);
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clk->cl.con_id = clk->name;
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clkdev_add(&clk->cl);
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int __init clk_register(struct clk *clk)
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if (clk_is_peripheral(clk)) {
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clk->mode = pmc_periph_mode;
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else if (clk_is_sys(clk)) {
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clk->mode = pmc_sys_mode;
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#ifdef CONFIG_AT91_PROGRAMMABLE_CLOCKS
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else if (clk_is_programmable(clk)) {
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clk->mode = pmc_sys_mode;
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init_programmable_clock(clk);
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/*------------------------------------------------------------------------*/
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static u32 __init at91_pll_rate(struct clk *pll, u32 freq, u32 reg)
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mul = (reg >> 16) & 0x7ff;
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static u32 __init at91_usb_rate(struct clk *pll, u32 freq, u32 reg)
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if (pll == &pllb && (reg & AT91_PMC_USB96M))
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static unsigned __init at91_pll_calc(unsigned main_freq, unsigned out_freq)
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unsigned i, div = 0, mul = 0, diff = 1 << 30;
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unsigned ret = (out_freq > 155000000) ? 0xbe00 : 0x3e00;
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/* PLL output max 240 MHz (or 180 MHz per errata) */
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if (out_freq > 240000000)
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for (i = 1; i < 256; i++) {
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unsigned input, mul1;
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* PLL input between 1MHz and 32MHz per spec, but lower
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* frequences seem necessary in some cases so allow 100K.
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* Warning: some newer products need 2MHz min.
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input = main_freq / i;
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if (cpu_is_at91sam9g20() && input < 2000000)
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if (input > 32000000)
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mul1 = out_freq / input;
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if (cpu_is_at91sam9g20() && mul > 63)
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diff1 = out_freq - input * mul1;
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if (i == 256 && diff > (out_freq >> 5))
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return ret | ((mul - 1) << 16) | div;
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static struct clk *const standard_pmc_clocks[] __initdata = {
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/* four primary clocks */
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/* PLLB generated USB full speed clock init */
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static void __init at91_pllb_usbfs_clock_init(unsigned long main_clock)
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* USB clock init: choose 48 MHz PLLB value,
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* disable 48MHz clock during usb peripheral suspend.
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* REVISIT: assumes MCK doesn't derive from PLLB!
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uhpck.parent = &pllb;
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at91_pllb_usb_init = at91_pll_calc(main_clock, 48000000 * 2) | AT91_PMC_USB96M;
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pllb.rate_hz = at91_pll_rate(&pllb, main_clock, at91_pllb_usb_init);
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if (cpu_is_at91rm9200()) {
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uhpck.pmc_mask = AT91RM9200_PMC_UHP;
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udpck.pmc_mask = AT91RM9200_PMC_UDP;
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at91_sys_write(AT91_PMC_SCER, AT91RM9200_PMC_MCKUDP);
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} else if (cpu_is_at91sam9260() || cpu_is_at91sam9261() ||
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cpu_is_at91sam9263() || cpu_is_at91sam9g20() ||
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cpu_is_at91sam9g10()) {
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uhpck.pmc_mask = AT91SAM926x_PMC_UHP;
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udpck.pmc_mask = AT91SAM926x_PMC_UDP;
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} else if (cpu_is_at91cap9()) {
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uhpck.pmc_mask = AT91CAP9_PMC_UHP;
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at91_sys_write(AT91_CKGR_PLLBR, 0);
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udpck.rate_hz = at91_usb_rate(&pllb, pllb.rate_hz, at91_pllb_usb_init);
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uhpck.rate_hz = at91_usb_rate(&pllb, pllb.rate_hz, at91_pllb_usb_init);
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/* UPLL generated USB full speed clock init */
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static void __init at91_upll_usbfs_clock_init(unsigned long main_clock)
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* USB clock init: choose 480 MHz from UPLL,
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unsigned int usbr = AT91_PMC_USBS_UPLL;
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/* Setup divider by 10 to reach 48 MHz */
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usbr |= ((10 - 1) << 8) & AT91_PMC_OHCIUSBDIV;
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at91_sys_write(AT91_PMC_USB, usbr);
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/* Now set uhpck values */
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uhpck.parent = &utmi_clk;
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uhpck.pmc_mask = AT91SAM926x_PMC_UHP;
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uhpck.rate_hz = utmi_clk.rate_hz;
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uhpck.rate_hz /= 1 + ((at91_sys_read(AT91_PMC_USB) & AT91_PMC_OHCIUSBDIV) >> 8);
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int __init at91_clock_init(unsigned long main_clock)
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unsigned tmp, freq, mckr;
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int pll_overclock = false;
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* When the bootloader initialized the main oscillator correctly,
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* there's no problem using the cycle counter. But if it didn't,
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* or when using oscillator bypass mode, we must be told the speed
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tmp = at91_sys_read(AT91_CKGR_MCFR);
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} while (!(tmp & AT91_PMC_MAINRDY));
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main_clock = (tmp & AT91_PMC_MAINF) * (AT91_SLOW_CLOCK / 16);
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main_clk.rate_hz = main_clock;
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/* report if PLLA is more than mildly overclocked */
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plla.rate_hz = at91_pll_rate(&plla, main_clock, at91_sys_read(AT91_CKGR_PLLAR));
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if (cpu_has_300M_plla()) {
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if (plla.rate_hz > 300000000)
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pll_overclock = true;
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} else if (cpu_has_800M_plla()) {
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if (plla.rate_hz > 800000000)
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pll_overclock = true;
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if (plla.rate_hz > 209000000)
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pll_overclock = true;
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pr_info("Clocks: PLLA overclocked, %ld MHz\n", plla.rate_hz / 1000000);
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if (cpu_is_at91sam9g45()) {
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mckr = at91_sys_read(AT91_PMC_MCKR);
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plla.rate_hz /= (1 << ((mckr & AT91_PMC_PLLADIV2) >> 12)); /* plla divisor by 2 */
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if (!cpu_has_pllb() && cpu_has_upll()) {
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/* setup UTMI clock as the fourth primary clock
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* (instead of pllb) */
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utmi_clk.type |= CLK_TYPE_PRIMARY;
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if (cpu_has_utmi()) {
687
* multiplier is hard-wired to 40
688
* (obtain the USB High Speed 480 MHz when input is 12 MHz)
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utmi_clk.rate_hz = 40 * utmi_clk.parent->rate_hz;
697
at91_pllb_usbfs_clock_init(main_clock);
699
/* assumes that we choose UPLL for USB and not PLLA */
700
at91_upll_usbfs_clock_init(main_clock);
703
* MCK and CPU derive from one of those primary clocks.
704
* For now, assume this parentage won't change.
706
mckr = at91_sys_read(AT91_PMC_MCKR);
707
mck.parent = at91_css_to_clk(mckr & AT91_PMC_CSS);
708
freq = mck.parent->rate_hz;
709
freq /= (1 << ((mckr & AT91_PMC_PRES) >> 2)); /* prescale */
710
if (cpu_is_at91rm9200()) {
711
mck.rate_hz = freq / (1 + ((mckr & AT91_PMC_MDIV) >> 8)); /* mdiv */
712
} else if (cpu_is_at91sam9g20()) {
713
mck.rate_hz = (mckr & AT91_PMC_MDIV) ?
714
freq / ((mckr & AT91_PMC_MDIV) >> 7) : freq; /* mdiv ; (x >> 7) = ((x >> 8) * 2) */
715
if (mckr & AT91_PMC_PDIV)
716
freq /= 2; /* processor clock division */
717
} else if (cpu_is_at91sam9g45()) {
718
mck.rate_hz = (mckr & AT91_PMC_MDIV) == AT91SAM9_PMC_MDIV_3 ?
719
freq / 3 : freq / (1 << ((mckr & AT91_PMC_MDIV) >> 8)); /* mdiv */
721
mck.rate_hz = freq / (1 << ((mckr & AT91_PMC_MDIV) >> 8)); /* mdiv */
724
/* Register the PMC's standard clocks */
725
for (i = 0; i < ARRAY_SIZE(standard_pmc_clocks); i++)
726
at91_clk_add(standard_pmc_clocks[i]);
732
at91_clk_add(&uhpck);
735
at91_clk_add(&udpck);
738
at91_clk_add(&utmi_clk);
740
/* MCK and CPU clock are "always on" */
743
printk("Clocks: CPU %u MHz, master %u MHz, main %u.%03u MHz\n",
744
freq / 1000000, (unsigned) mck.rate_hz / 1000000,
745
(unsigned) main_clock / 1000000,
746
((unsigned) main_clock % 1000000) / 1000);
752
* Several unused clocks may be active. Turn them off.
754
static int __init at91_clock_reset(void)
756
unsigned long pcdr = 0;
757
unsigned long scdr = 0;
760
list_for_each_entry(clk, &clocks, node) {
764
if (clk->mode == pmc_periph_mode)
765
pcdr |= clk->pmc_mask;
767
if (clk->mode == pmc_sys_mode)
768
scdr |= clk->pmc_mask;
770
pr_debug("Clocks: disable unused %s\n", clk->name);
773
at91_sys_write(AT91_PMC_PCDR, pcdr);
774
at91_sys_write(AT91_PMC_SCDR, scdr);
778
late_initcall(at91_clock_reset);