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// SPDX-License-Identifier: GPL-2.0
/*
* I2C driver for stand-alone PCF8584 style adapters on Zorro cards
*
* Original ICY documentation can be found on Aminet:
* https://aminet.net/package/docs/hard/icy
*
* There has been a modern community re-print of this design in 2019:
* https://www.a1k.org/forum/index.php?threads/70106/
*
* The card is basically a Philips PCF8584 connected straight to the
* beginning of the AutoConfig'd address space (register S1 on base+2),
* with /INT on /INT2 on the Zorro bus.
*
* Copyright (c) 2019 Max Staudt <max@enpas.org>
*
* This started as a fork of i2c-elektor.c and has evolved since.
* Thanks go to its authors for providing a base to grow on.
*
*
* IRQ support is currently not implemented.
*
* As it turns out, i2c-algo-pcf is really written with i2c-elektor's
* edge-triggered ISA interrupts in mind, while the Amiga's Zorro bus has
* level-triggered interrupts. This means that once an interrupt occurs, we
* have to tell the PCF8584 to shut up immediately, or it will keep the
* interrupt line busy and cause an IRQ storm.
* However, because of the PCF8584's host-side protocol, there is no good
* way to just quieten it without side effects. Rather, we have to perform
* the next read/write operation straight away, which will reset the /INT
* pin. This entails re-designing the core of i2c-algo-pcf in the future.
* For now, we never request an IRQ from the PCF8584, and poll it instead.
*/
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-pcf.h>
#include <asm/amigaints.h>
#include <linux/zorro.h>
#include "../algos/i2c-algo-pcf.h"
struct icy_i2c {
struct i2c_adapter adapter;
void __iomem *reg_s0;
void __iomem *reg_s1;
};
/*
* Functions called by i2c-algo-pcf
*/
static void icy_pcf_setpcf(void *data, int ctl, int val)
{
struct icy_i2c *i2c = (struct icy_i2c *)data;
u8 __iomem *address = ctl ? i2c->reg_s1 : i2c->reg_s0;
z_writeb(val, address);
}
static int icy_pcf_getpcf(void *data, int ctl)
{
struct icy_i2c *i2c = (struct icy_i2c *)data;
u8 __iomem *address = ctl ? i2c->reg_s1 : i2c->reg_s0;
return z_readb(address);
}
static int icy_pcf_getown(void *data)
{
return 0x55;
}
static int icy_pcf_getclock(void *data)
{
return 0x1c;
}
static void icy_pcf_waitforpin(void *data)
{
usleep_range(50, 150);
}
/*
* Main i2c-icy part
*/
static int icy_probe(struct zorro_dev *z,
const struct zorro_device_id *ent)
{
struct icy_i2c *i2c;
struct i2c_algo_pcf_data *algo_data;
i2c = devm_kzalloc(&z->dev, sizeof(*i2c), GFP_KERNEL);
if (!i2c)
return -ENOMEM;
algo_data = devm_kzalloc(&z->dev, sizeof(*algo_data), GFP_KERNEL);
if (!algo_data)
return -ENOMEM;
dev_set_drvdata(&z->dev, i2c);
i2c->adapter.dev.parent = &z->dev;
i2c->adapter.owner = THIS_MODULE;
/* i2c->adapter.algo assigned by i2c_pcf_add_bus() */
i2c->adapter.algo_data = algo_data;
strlcpy(i2c->adapter.name, "ICY I2C Zorro adapter",
sizeof(i2c->adapter.name));
if (!devm_request_mem_region(&z->dev,
z->resource.start,
4, i2c->adapter.name))
return -ENXIO;
/* Driver private data */
i2c->reg_s0 = ZTWO_VADDR(z->resource.start);
i2c->reg_s1 = ZTWO_VADDR(z->resource.start + 2);
algo_data->data = i2c;
algo_data->setpcf = icy_pcf_setpcf;
algo_data->getpcf = icy_pcf_getpcf;
algo_data->getown = icy_pcf_getown;
algo_data->getclock = icy_pcf_getclock;
algo_data->waitforpin = icy_pcf_waitforpin;
if (i2c_pcf_add_bus(&i2c->adapter)) {
dev_err(&z->dev, "i2c_pcf_add_bus() failed\n");
return -ENXIO;
}
dev_info(&z->dev, "ICY I2C controller at %pa, IRQ not implemented\n",
&z->resource.start);
return 0;
}
static void icy_remove(struct zorro_dev *z)
{
struct icy_i2c *i2c = dev_get_drvdata(&z->dev);
i2c_del_adapter(&i2c->adapter);
}
static const struct zorro_device_id icy_zorro_tbl[] = {
{ ZORRO_ID(VMC, 15, 0), },
{ 0 }
};
MODULE_DEVICE_TABLE(zorro, icy_zorro_tbl);
static struct zorro_driver icy_driver = {
.name = "i2c-icy",
.id_table = icy_zorro_tbl,
.probe = icy_probe,
.remove = icy_remove,
};
module_driver(icy_driver,
zorro_register_driver,
zorro_unregister_driver);
MODULE_AUTHOR("Max Staudt <max@enpas.org>");
MODULE_DESCRIPTION("I2C bus via PCF8584 on ICY Zorro card");
MODULE_LICENSE("GPL v2");
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