/* SPDX-License-Identifier: GPL-2.0+ */
/*
 * comedi_8254.h
 * Generic 8254 timer/counter support
 * Copyright (C) 2014 H Hartley Sweeten <hsweeten@visionengravers.com>
 *
 * COMEDI - Linux Control and Measurement Device Interface
 * Copyright (C) 2000 David A. Schleef <ds@schleef.org>
 */

#ifndef _COMEDI_8254_H
#define _COMEDI_8254_H

#include <linux/types.h>
#include <linux/errno.h>
#include <linux/err.h>

struct comedi_device;
struct comedi_insn;
struct comedi_subdevice;

/*
 * Common oscillator base values in nanoseconds
 */
#define I8254_OSC_BASE_10MHZ    100
#define I8254_OSC_BASE_5MHZ     200
#define I8254_OSC_BASE_4MHZ     250
#define I8254_OSC_BASE_2MHZ     500
#define I8254_OSC_BASE_1MHZ     1000
#define I8254_OSC_BASE_100KHZ   10000
#define I8254_OSC_BASE_10KHZ    100000
#define I8254_OSC_BASE_1KHZ     1000000

/*
 * I/O access size used to read/write registers
 */
#define I8254_IO8               1
#define I8254_IO16              2
#define I8254_IO32              4

/*
 * Register map for generic 8254 timer (I8254_IO8 with 0 regshift)
 */
#define I8254_COUNTER0_REG              0x00
#define I8254_COUNTER1_REG              0x01
#define I8254_COUNTER2_REG              0x02
#define I8254_CTRL_REG                  0x03
#define I8254_CTRL_SEL_CTR(x)           ((x) << 6)
#define I8254_CTRL_READBACK(x)          (I8254_CTRL_SEL_CTR(3) | BIT(x))
#define I8254_CTRL_READBACK_COUNT       I8254_CTRL_READBACK(4)
#define I8254_CTRL_READBACK_STATUS      I8254_CTRL_READBACK(5)
#define I8254_CTRL_READBACK_SEL_CTR(x)  (2 << (x))
#define I8254_CTRL_RW(x)                (((x) & 0x3) << 4)
#define I8254_CTRL_LATCH                I8254_CTRL_RW(0)
#define I8254_CTRL_LSB_ONLY             I8254_CTRL_RW(1)
#define I8254_CTRL_MSB_ONLY             I8254_CTRL_RW(2)
#define I8254_CTRL_LSB_MSB              I8254_CTRL_RW(3)

/* counter maps zero to 0x10000 */
#define I8254_MAX_COUNT                 0x10000

struct comedi_8254;

/**
 * typedef comedi_8254_iocb_fn - call-back function type for 8254 register access
 * @i8254:              pointer to struct comedi_8254
 * @dir:                direction (0 = read, 1 = write)
 * @reg:                register number
 * @val:                value to write
 *
 * Return: Register value when reading, 0 when writing.
 */
typedef unsigned int comedi_8254_iocb_fn(struct comedi_8254 *i8254, int dir,
                                         unsigned int reg, unsigned int val);

/**
 * struct comedi_8254 - private data used by this module
 * @iocb:               I/O call-back function for register access
 * @context:            context for register access (e.g. a base address)
 * @iosize:             I/O size used to access the registers (b/w/l)
 * @regshift:           register gap shift
 * @osc_base:           cascaded oscillator speed in ns
 * @divisor:            divisor for single counter
 * @divisor1:           divisor loaded into first cascaded counter
 * @divisor2:           divisor loaded into second cascaded counter
 * @next_div:           next divisor for single counter
 * @next_div1:          next divisor to use for first cascaded counter
 * @next_div2:          next divisor to use for second cascaded counter
 * @clock_src:          current clock source for each counter (driver specific)
 * @gate_src:           current gate source  for each counter (driver specific)
 * @busy:               flags used to indicate that a counter is "busy"
 * @insn_config:        driver specific (*insn_config) callback
 */
struct comedi_8254 {
        comedi_8254_iocb_fn *iocb;
        unsigned long context;
        unsigned int iosize;
        unsigned int regshift;
        unsigned int osc_base;
        unsigned int divisor;
        unsigned int divisor1;
        unsigned int divisor2;
        unsigned int next_div;
        unsigned int next_div1;
        unsigned int next_div2;
        unsigned int clock_src[3];
        unsigned int gate_src[3];
        bool busy[3];

        int (*insn_config)(struct comedi_device *dev,
                           struct comedi_subdevice *s,
                           struct comedi_insn *insn, unsigned int *data);
};

unsigned int comedi_8254_status(struct comedi_8254 *i8254,
                                unsigned int counter);
unsigned int comedi_8254_read(struct comedi_8254 *i8254, unsigned int counter);
void comedi_8254_write(struct comedi_8254 *i8254,
                       unsigned int counter, unsigned int val);

int comedi_8254_set_mode(struct comedi_8254 *i8254,
                         unsigned int counter, unsigned int mode);
int comedi_8254_load(struct comedi_8254 *i8254,
                     unsigned int counter, unsigned int val, unsigned int mode);

void comedi_8254_pacer_enable(struct comedi_8254 *i8254,
                              unsigned int counter1, unsigned int counter2,
                              bool enable);
void comedi_8254_update_divisors(struct comedi_8254 *i8254);
void comedi_8254_cascade_ns_to_timer(struct comedi_8254 *i8254,
                                     unsigned int *nanosec, unsigned int flags);
void comedi_8254_ns_to_timer(struct comedi_8254 *i8254,
                             unsigned int *nanosec, unsigned int flags);

void comedi_8254_set_busy(struct comedi_8254 *i8254,
                          unsigned int counter, bool busy);

void comedi_8254_subdevice_init(struct comedi_subdevice *s,
                                struct comedi_8254 *i8254);

#ifdef CONFIG_HAS_IOPORT
struct comedi_8254 *comedi_8254_io_alloc(unsigned long iobase,
                                         unsigned int osc_base,
                                         unsigned int iosize,
                                         unsigned int regshift);
#else
static inline struct comedi_8254 *comedi_8254_io_alloc(unsigned long iobase,
                                                       unsigned int osc_base,
                                                       unsigned int iosize,
                                                       unsigned int regshift)
{
        return ERR_PTR(-ENXIO);
}
#endif

struct comedi_8254 *comedi_8254_mm_alloc(void __iomem *mmio,
                                         unsigned int osc_base,
                                         unsigned int iosize,
                                         unsigned int regshift);

#endif  /* _COMEDI_8254_H */