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// SPDX-License-Identifier: GPL-2.0
/*
* Intel 8255 Programmable Peripheral Interface
* Copyright (C) 2022 William Breathitt Gray
*/
#include <linux/bitmap.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include "gpio-i8255.h"
#define I8255_CONTROL_PORTC_LOWER_DIRECTION BIT(0)
#define I8255_CONTROL_PORTB_DIRECTION BIT(1)
#define I8255_CONTROL_PORTC_UPPER_DIRECTION BIT(3)
#define I8255_CONTROL_PORTA_DIRECTION BIT(4)
#define I8255_CONTROL_MODE_SET BIT(7)
#define I8255_PORTA 0
#define I8255_PORTB 1
#define I8255_PORTC 2
static int i8255_get_port(struct i8255 __iomem *const ppi,
const unsigned long io_port, const unsigned long mask)
{
const unsigned long bank = io_port / 3;
const unsigned long ppi_port = io_port % 3;
return ioread8(&ppi[bank].port[ppi_port]) & mask;
}
static u8 i8255_direction_mask(const unsigned long offset)
{
const unsigned long port_offset = offset % 8;
const unsigned long io_port = offset / 8;
const unsigned long ppi_port = io_port % 3;
switch (ppi_port) {
case I8255_PORTA:
return I8255_CONTROL_PORTA_DIRECTION;
case I8255_PORTB:
return I8255_CONTROL_PORTB_DIRECTION;
case I8255_PORTC:
/* Port C can be configured by nibble */
if (port_offset >= 4)
return I8255_CONTROL_PORTC_UPPER_DIRECTION;
return I8255_CONTROL_PORTC_LOWER_DIRECTION;
default:
/* Should never reach this path */
return 0;
}
}
static void i8255_set_port(struct i8255 __iomem *const ppi,
struct i8255_state *const state,
const unsigned long io_port,
const unsigned long mask, const unsigned long bits)
{
const unsigned long bank = io_port / 3;
const unsigned long ppi_port = io_port % 3;
unsigned long flags;
unsigned long out_state;
spin_lock_irqsave(&state[bank].lock, flags);
out_state = ioread8(&ppi[bank].port[ppi_port]);
out_state = (out_state & ~mask) | (bits & mask);
iowrite8(out_state, &ppi[bank].port[ppi_port]);
spin_unlock_irqrestore(&state[bank].lock, flags);
}
/**
* i8255_direction_input - configure signal offset as input
* @ppi: Intel 8255 Programmable Peripheral Interface banks
* @state: devices states of the respective PPI banks
* @offset: signal offset to configure as input
*
* Configures a signal @offset as input for the respective Intel 8255
* Programmable Peripheral Interface (@ppi) banks. The @state control_state
* values are updated to reflect the new configuration.
*/
void i8255_direction_input(struct i8255 __iomem *const ppi,
struct i8255_state *const state,
const unsigned long offset)
{
const unsigned long io_port = offset / 8;
const unsigned long bank = io_port / 3;
unsigned long flags;
spin_lock_irqsave(&state[bank].lock, flags);
state[bank].control_state |= I8255_CONTROL_MODE_SET;
state[bank].control_state |= i8255_direction_mask(offset);
iowrite8(state[bank].control_state, &ppi[bank].control);
spin_unlock_irqrestore(&state[bank].lock, flags);
}
EXPORT_SYMBOL_NS_GPL(i8255_direction_input, I8255);
/**
* i8255_direction_output - configure signal offset as output
* @ppi: Intel 8255 Programmable Peripheral Interface banks
* @state: devices states of the respective PPI banks
* @offset: signal offset to configure as output
* @value: signal value to output
*
* Configures a signal @offset as output for the respective Intel 8255
* Programmable Peripheral Interface (@ppi) banks and sets the respective signal
* output to the desired @value. The @state control_state values are updated to
* reflect the new configuration.
*/
void i8255_direction_output(struct i8255 __iomem *const ppi,
struct i8255_state *const state,
const unsigned long offset,
const unsigned long value)
{
const unsigned long io_port = offset / 8;
const unsigned long bank = io_port / 3;
unsigned long flags;
spin_lock_irqsave(&state[bank].lock, flags);
state[bank].control_state |= I8255_CONTROL_MODE_SET;
state[bank].control_state &= ~i8255_direction_mask(offset);
iowrite8(state[bank].control_state, &ppi[bank].control);
spin_unlock_irqrestore(&state[bank].lock, flags);
i8255_set(ppi, state, offset, value);
}
EXPORT_SYMBOL_NS_GPL(i8255_direction_output, I8255);
/**
* i8255_get - get signal value at signal offset
* @ppi: Intel 8255 Programmable Peripheral Interface banks
* @offset: offset of signal to get
*
* Returns the signal value (0=low, 1=high) for the signal at @offset for the
* respective Intel 8255 Programmable Peripheral Interface (@ppi) banks.
*/
int i8255_get(struct i8255 __iomem *const ppi, const unsigned long offset)
{
const unsigned long io_port = offset / 8;
const unsigned long offset_mask = BIT(offset % 8);
return !!i8255_get_port(ppi, io_port, offset_mask);
}
EXPORT_SYMBOL_NS_GPL(i8255_get, I8255);
/**
* i8255_get_direction - get the I/O direction for a signal offset
* @state: devices states of the respective PPI banks
* @offset: offset of signal to get direction
*
* Returns the signal direction (0=output, 1=input) for the signal at @offset.
*/
int i8255_get_direction(const struct i8255_state *const state,
const unsigned long offset)
{
const unsigned long io_port = offset / 8;
const unsigned long bank = io_port / 3;
return !!(state[bank].control_state & i8255_direction_mask(offset));
}
EXPORT_SYMBOL_NS_GPL(i8255_get_direction, I8255);
/**
* i8255_get_multiple - get multiple signal values at multiple signal offsets
* @ppi: Intel 8255 Programmable Peripheral Interface banks
* @mask: mask of signals to get
* @bits: bitmap to store signal values
* @ngpio: number of GPIO signals of the respective PPI banks
*
* Stores in @bits the values (0=low, 1=high) for the signals defined by @mask
* for the respective Intel 8255 Programmable Peripheral Interface (@ppi) banks.
*/
void i8255_get_multiple(struct i8255 __iomem *const ppi,
const unsigned long *const mask,
unsigned long *const bits, const unsigned long ngpio)
{
unsigned long offset;
unsigned long port_mask;
unsigned long io_port;
unsigned long port_state;
bitmap_zero(bits, ngpio);
for_each_set_clump8(offset, port_mask, mask, ngpio) {
io_port = offset / 8;
port_state = i8255_get_port(ppi, io_port, port_mask);
bitmap_set_value8(bits, port_state, offset);
}
}
EXPORT_SYMBOL_NS_GPL(i8255_get_multiple, I8255);
/**
* i8255_mode0_output - configure all PPI ports to MODE 0 output mode
* @ppi: Intel 8255 Programmable Peripheral Interface bank
*
* Configures all Intel 8255 Programmable Peripheral Interface (@ppi) ports to
* MODE 0 (Basic Input/Output) output mode.
*/
void i8255_mode0_output(struct i8255 __iomem *const ppi)
{
iowrite8(I8255_CONTROL_MODE_SET, &ppi->control);
}
EXPORT_SYMBOL_NS_GPL(i8255_mode0_output, I8255);
/**
* i8255_set - set signal value at signal offset
* @ppi: Intel 8255 Programmable Peripheral Interface banks
* @state: devices states of the respective PPI banks
* @offset: offset of signal to set
* @value: value of signal to set
*
* Assigns output @value for the signal at @offset for the respective Intel 8255
* Programmable Peripheral Interface (@ppi) banks.
*/
void i8255_set(struct i8255 __iomem *const ppi, struct i8255_state *const state,
const unsigned long offset, const unsigned long value)
{
const unsigned long io_port = offset / 8;
const unsigned long port_offset = offset % 8;
const unsigned long mask = BIT(port_offset);
const unsigned long bits = value << port_offset;
i8255_set_port(ppi, state, io_port, mask, bits);
}
EXPORT_SYMBOL_NS_GPL(i8255_set, I8255);
/**
* i8255_set_multiple - set signal values at multiple signal offsets
* @ppi: Intel 8255 Programmable Peripheral Interface banks
* @state: devices states of the respective PPI banks
* @mask: mask of signals to set
* @bits: bitmap of signal output values
* @ngpio: number of GPIO signals of the respective PPI banks
*
* Assigns output values defined by @bits for the signals defined by @mask for
* the respective Intel 8255 Programmable Peripheral Interface (@ppi) banks.
*/
void i8255_set_multiple(struct i8255 __iomem *const ppi,
struct i8255_state *const state,
const unsigned long *const mask,
const unsigned long *const bits,
const unsigned long ngpio)
{
unsigned long offset;
unsigned long port_mask;
unsigned long io_port;
unsigned long value;
for_each_set_clump8(offset, port_mask, mask, ngpio) {
io_port = offset / 8;
value = bitmap_get_value8(bits, offset);
i8255_set_port(ppi, state, io_port, port_mask, value);
}
}
EXPORT_SYMBOL_NS_GPL(i8255_set_multiple, I8255);
/**
* i8255_state_init - initialize i8255_state structure
* @state: devices states of the respective PPI banks
* @nbanks: number of Intel 8255 Programmable Peripheral Interface banks
*
* Initializes the @state of each Intel 8255 Programmable Peripheral Interface
* bank for use in i8255 library functions.
*/
void i8255_state_init(struct i8255_state *const state,
const unsigned long nbanks)
{
unsigned long bank;
for (bank = 0; bank < nbanks; bank++)
spin_lock_init(&state[bank].lock);
}
EXPORT_SYMBOL_NS_GPL(i8255_state_init, I8255);
MODULE_AUTHOR("William Breathitt Gray");
MODULE_DESCRIPTION("Intel 8255 Programmable Peripheral Interface");
MODULE_LICENSE("GPL");