[U-Boot] [PATCH v3] ARM: s5p: pwm driver support

Chander M. Kashyap chander.kashyap at gmail.com
Mon Mar 5 12:13:13 CET 2012


Dear Donghwa Lee,

On Tue, Mar 8, 2011 at 7:12 AM, Donghwa Lee <dh09.lee at samsung.com> wrote:
> This is common pwm driver of S5P.
>
> Signed-off-by: Donghwa Lee <dh09.lee at samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park at samsung.com>
> ---
> Changes since v2:
> - Timer4 was blocked to access compare buffer register
> - code clean
>
>  arch/arm/cpu/armv7/s5p-common/Makefile  |    1 +
>  arch/arm/cpu/armv7/s5p-common/pwm.c     |  198 +++++++++++++++++++++++++++++++
>  arch/arm/include/asm/arch-s5pc1xx/pwm.h |    7 +
>  arch/arm/include/asm/arch-s5pc2xx/pwm.h |    7 +
>  include/pwm.h                           |   31 +++++
>  5 files changed, 244 insertions(+), 0 deletions(-)
>  create mode 100644 arch/arm/cpu/armv7/s5p-common/pwm.c
>  create mode 100644 include/pwm.h
>
> diff --git a/arch/arm/cpu/armv7/s5p-common/Makefile b/arch/arm/cpu/armv7/s5p-common/Makefile
> index 922cd95..ce0a41e 100644
> --- a/arch/arm/cpu/armv7/s5p-common/Makefile
> +++ b/arch/arm/cpu/armv7/s5p-common/Makefile
> @@ -27,6 +27,7 @@ LIB   = $(obj)libs5p-common.o
>
>  COBJS-y                += cpu_info.o
>  COBJS-y                += timer.o
> +COBJS-$(CONFIG_PWM)            += pwm.o
>
>  SRCS   := $(SOBJS:.o=.S) $(COBJS:.o=.c)
>  OBJS   := $(addprefix $(obj),$(COBJS-y) $(SOBJS))
> 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..29e996e
> --- /dev/null
> +++ b/arch/arm/cpu/armv7/s5p-common/pwm.c
> @@ -0,0 +1,198 @@
> +/*
> + * Copyright (C) 2011 Samsung Electronics
> + *
> + * Donghwa Lee <dh09.lee at 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>
> +
> +#define PRESCALER_0            (8 - 1)         /* prescaler of timer 0, 1 */
> +#define PRESCALER_1            (16 - 1)        /* prescaler of timer 2, 3, 4 */
> +#define MUX_DIV_1              0               /* 1/1 period */
> +#define MUX_DIV_2              1               /* 1/2 period */
> +#define MUX_DIV_4              2               /* 1/4 period */
> +#define MUX_DIV_8              3               /* 1/8 period */
> +#define MUX_DIV_16             4               /* 1/16 period */
> +
> +#define MUX_DIV_SHIFT(x)       (x * 4)
> +
> +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_HZ (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 period;
> +       unsigned long tcon;
> +       unsigned long tcnt;
> +       unsigned long timer_rate_hz;
> +       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_HZ || duty_ns > NS_IN_HZ)
> +               return -ERANGE;
> +
> +       if (duty_ns > period_ns)
> +               return -EINVAL;
> +
> +       period = NS_IN_HZ / period_ns;
periad_ns = 0; This leads to divide by zero. How divede by zero is handeled.
> +
> +       /* Check to see if we are changing the clock rate of the PWM */
> +       tin_rate = pwm_calc_tin(pwm_id, period);
> +       timer_rate_hz = tin_rate;
> +
> +       tin_ns = NS_IN_HZ / tin_rate;
> +       tcnt = period_ns / tin_ns;
> +
> +       /* Note, counters count down */
> +       tcmp = duty_ns / tin_ns;
> +       tcmp = tcnt - tcmp;
> +
> +       /*
> +        * the pwm hw only checks the compare register after a decrement,
> +        * so the pin never toggles if tcmp = tcnt
> +        */
> +       if (tcmp == tcnt)
> +               tcmp--;
> +
> +       if (tcmp < 0)
> +               tcmp = 0;
> +
> +       /* Update the PWM register block. */
> +       offset = pwm_id * 0xc;
> +       writel(tcnt, &pwm->tcntb0 + offset);
> +       if (pwm_id < 4)
> +               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 timer_rate_hz;
> +       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);
> +
> +       timer_rate_hz = get_pwm_clk() / ((prescaler + 1) *
> +                       (div + 1));
> +
> +       timer_rate_hz = timer_rate_hz / 100;
> +
> +       /* set count value */
> +       offset = pwm_id * 0xc;
> +       writel(timer_rate_hz, &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;
> +}
> diff --git a/arch/arm/include/asm/arch-s5pc1xx/pwm.h b/arch/arm/include/asm/arch-s5pc1xx/pwm.h
> index 0369968..ec62075 100644
> --- a/arch/arm/include/asm/arch-s5pc1xx/pwm.h
> +++ b/arch/arm/include/asm/arch-s5pc1xx/pwm.h
> @@ -29,6 +29,13 @@
>  /* start bit of PWM Timer 4 */
>  #define TCON4_START            (1 << 20)
>
> +#define TCON_OFFSET(x)         ((x + 1) * (!!x) << 2)
> +
> +#define TCON_START(x)          (1 << TCON_OFFSET(x))
> +#define TCON_UPDATE(x)         (1 << (TCON_OFFSET(x) + 1))
> +#define TCON_INVERTER(x)       (1 << (TCON_OFFSET(x) + 2))
> +#define TCON_AUTO_RELOAD(x)    (1 << (TCON_OFFSET(x) + 3))
> +
>  #ifndef __ASSEMBLY__
>  struct s5p_timer {
>        unsigned int    tcfg0;
> diff --git a/arch/arm/include/asm/arch-s5pc2xx/pwm.h b/arch/arm/include/asm/arch-s5pc2xx/pwm.h
> index 0369968..ec62075 100644
> --- a/arch/arm/include/asm/arch-s5pc2xx/pwm.h
> +++ b/arch/arm/include/asm/arch-s5pc2xx/pwm.h
> @@ -29,6 +29,13 @@
>  /* start bit of PWM Timer 4 */
>  #define TCON4_START            (1 << 20)
>
> +#define TCON_OFFSET(x)         ((x + 1) * (!!x) << 2)
> +
> +#define TCON_START(x)          (1 << TCON_OFFSET(x))
> +#define TCON_UPDATE(x)         (1 << (TCON_OFFSET(x) + 1))
> +#define TCON_INVERTER(x)       (1 << (TCON_OFFSET(x) + 2))
> +#define TCON_AUTO_RELOAD(x)    (1 << (TCON_OFFSET(x) + 3))
> +
>  #ifndef __ASSEMBLY__
>  struct s5p_timer {
>        unsigned int    tcfg0;
> diff --git a/include/pwm.h b/include/pwm.h
> new file mode 100644
> index 0000000..13acf85
> --- /dev/null
> +++ b/include/pwm.h
> @@ -0,0 +1,31 @@
> +/*
> + * header file for pwm driver.
> + *
> + * Copyright (c) 2011 samsung electronics
> + * Donghwa Lee <dh09.lee at samsung.com>
> + *
> + * 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
> + */
> +
> +#ifndef _pwm_h_
> +#define _pwm_h_
> +
> +int    pwm_init                (int pwm_id, int div, int invert);
> +int    pwm_config              (int pwm_id, int duty_ns, int period_ns);
> +int    pwm_enable              (int pwm_id);
> +void   pwm_disable             (int pwm_id);
> +
> +#endif /* _pwm_h_ */
> --
> 1.6.0.4
>
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-- 
thanks and regards,
Chander M. Kashyap
Contact Number: +919740798700
------- TENSION LENE KA NAHI, DENE KE-----


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