diff options
Diffstat (limited to 'arch/arm/cpu/armv7/s5p-common/pwm.c')
| -rw-r--r-- | arch/arm/cpu/armv7/s5p-common/pwm.c | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/arch/arm/cpu/armv7/s5p-common/pwm.c b/arch/arm/cpu/armv7/s5p-common/pwm.c new file mode 100644 index 0000000..6f401b8 --- /dev/null +++ b/arch/arm/cpu/armv7/s5p-common/pwm.c @@ -0,0 +1,187 @@ +/* + * Copyright (C) 2011 Samsung Electronics + * + * Donghwa Lee <dh09.lee@samsung.com> + * + * See file CREDITS for list of people who contributed to this + * project. + * + * 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 program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * 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., 59 Temple Place, Suite 330, Boston, + * MA 02111-1307 USA + */ + +#include <common.h> +#include <errno.h> +#include <pwm.h> +#include <asm/io.h> +#include <asm/arch/pwm.h> +#include <asm/arch/clk.h> + +int pwm_enable(int pwm_id) +{ + const struct s5p_timer *pwm = + (struct s5p_timer *)samsung_get_base_timer(); + unsigned long tcon; + + tcon = readl(&pwm->tcon); + tcon |= TCON_START(pwm_id); + + writel(tcon, &pwm->tcon); + + return 0; +} + +void pwm_disable(int pwm_id) +{ + const struct s5p_timer *pwm = + (struct s5p_timer *)samsung_get_base_timer(); + unsigned long tcon; + + tcon = readl(&pwm->tcon); + tcon &= ~TCON_START(pwm_id); + + writel(tcon, &pwm->tcon); +} + +static unsigned long pwm_calc_tin(int pwm_id, unsigned long freq) +{ + unsigned long tin_parent_rate; + unsigned int div; + + tin_parent_rate = get_pwm_clk(); + + for (div = 2; div <= 16; div *= 2) { + if ((tin_parent_rate / (div << 16)) < freq) + return tin_parent_rate / div; + } + + return tin_parent_rate / 16; +} + +#define NS_IN_SEC 1000000000UL + +int pwm_config(int pwm_id, int duty_ns, int period_ns) +{ + const struct s5p_timer *pwm = + (struct s5p_timer *)samsung_get_base_timer(); + unsigned int offset; + unsigned long tin_rate; + unsigned long tin_ns; + unsigned long frequency; + unsigned long tcon; + unsigned long tcnt; + unsigned long tcmp; + + /* + * We currently avoid using 64bit arithmetic by using the + * fact that anything faster than 1GHz is easily representable + * by 32bits. + */ + if (period_ns > NS_IN_SEC || duty_ns > NS_IN_SEC || period_ns == 0) + return -ERANGE; + + if (duty_ns > period_ns) + return -EINVAL; + + frequency = NS_IN_SEC / period_ns; + + /* Check to see if we are changing the clock rate of the PWM */ + tin_rate = pwm_calc_tin(pwm_id, frequency); + + tin_ns = NS_IN_SEC / tin_rate; + tcnt = period_ns / tin_ns; + + /* Note, counters count down */ + tcmp = duty_ns / tin_ns; + tcmp = tcnt - tcmp; + + /* Update the PWM register block. */ + offset = pwm_id * 3; + if (pwm_id < 4) { + writel(tcnt, &pwm->tcntb0 + offset); + writel(tcmp, &pwm->tcmpb0 + offset); + } + + tcon = readl(&pwm->tcon); + tcon |= TCON_UPDATE(pwm_id); + if (pwm_id < 4) + tcon |= TCON_AUTO_RELOAD(pwm_id); + else + tcon |= TCON4_AUTO_RELOAD; + writel(tcon, &pwm->tcon); + + tcon &= ~TCON_UPDATE(pwm_id); + writel(tcon, &pwm->tcon); + + return 0; +} + +int pwm_init(int pwm_id, int div, int invert) +{ + u32 val; + const struct s5p_timer *pwm = + (struct s5p_timer *)samsung_get_base_timer(); + unsigned long ticks_per_period; + unsigned int offset, prescaler; + + /* + * Timer Freq(HZ) = + * PWM_CLK / { (prescaler_value + 1) * (divider_value) } + */ + + val = readl(&pwm->tcfg0); + if (pwm_id < 2) { + prescaler = PRESCALER_0; + val &= ~0xff; + val |= (prescaler & 0xff); + } else { + prescaler = PRESCALER_1; + val &= ~(0xff << 8); + val |= (prescaler & 0xff) << 8; + } + writel(val, &pwm->tcfg0); + val = readl(&pwm->tcfg1); + val &= ~(0xf << MUX_DIV_SHIFT(pwm_id)); + val |= (div & 0xf) << MUX_DIV_SHIFT(pwm_id); + writel(val, &pwm->tcfg1); + + if (pwm_id == 4) { + /* + * TODO(sjg): Use this as a countdown timer for now. We count + * down from the maximum value to 0, then reset. + */ + ticks_per_period = -1UL; + } else { + const unsigned long pwm_hz = 1000; + unsigned long timer_rate_hz = get_pwm_clk() / + ((prescaler + 1) * (1 << div)); + + ticks_per_period = timer_rate_hz / pwm_hz; + } + + /* set count value */ + offset = pwm_id * 3; + + writel(ticks_per_period, &pwm->tcntb0 + offset); + + val = readl(&pwm->tcon) & ~(0xf << TCON_OFFSET(pwm_id)); + if (invert && (pwm_id < 4)) + val |= TCON_INVERTER(pwm_id); + writel(val, &pwm->tcon); + + pwm_enable(pwm_id); + + return 0; +} |
