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    Subject[PATCH v4 1/3] i2c/busses: Add i2c-icy for I2C on m68k/Amiga
    Date
    This is the i2c-icy driver for the ICY board for Amiga computers.
    It connects a PCF8584 I2C controller to the Zorro bus, providing I2C
    connectivity. The original documentation can be found on Aminet:

    https://aminet.net/package/docs/hard/icy

    IRQ support is currently not implemented, as i2c-algo-pcf is built for
    the ISA bus and a straight implementation of the same stack locks up a
    Zorro machine.

    v3: Fixed %pa format string
    Dropped adapter class.
    Clarified licence.
    Removed clock parameter.

    v2: Matched function names to callbacks from i2c-algo-pcf
    Used z_readb()/z_writeb()
    Removed BROKEN_ON_SMP in Kconfig
    Moved LTC2990 to a separate commit

    Signed-off-by: Max Staudt <max@enpas.org>
    ---
    MAINTAINERS | 6 ++
    drivers/i2c/busses/Kconfig | 11 +++
    drivers/i2c/busses/Makefile | 1 +
    drivers/i2c/busses/i2c-icy.c | 183 +++++++++++++++++++++++++++++++++++++++++++
    4 files changed, 201 insertions(+)
    create mode 100644 drivers/i2c/busses/i2c-icy.c

    diff --git a/MAINTAINERS b/MAINTAINERS
    index 1be025959..70336c083 100644
    --- a/MAINTAINERS
    +++ b/MAINTAINERS
    @@ -7705,6 +7705,12 @@ S: Maintained
    F: drivers/mfd/lpc_ich.c
    F: drivers/gpio/gpio-ich.c

    +ICY I2C DRIVER
    +M: Max Staudt <max@enpas.org>
    +L: linux-i2c@vger.kernel.org
    +S: Maintained
    +F: drivers/i2c/busses/i2c-icy.c
    +
    IDE SUBSYSTEM
    M: "David S. Miller" <davem@davemloft.net>
    L: linux-ide@vger.kernel.org
    diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
    index ee5dfb5ae..9e57e1101 100644
    --- a/drivers/i2c/busses/Kconfig
    +++ b/drivers/i2c/busses/Kconfig
    @@ -1300,6 +1300,17 @@ config I2C_ELEKTOR
    This support is also available as a module. If so, the module
    will be called i2c-elektor.

    +config I2C_ICY
    + tristate "ICY Zorro card"
    + depends on ZORRO
    + select I2C_ALGOPCF
    + help
    + This supports the PCF8584 Zorro bus I2C adapter, known as ICY.
    + Say Y if you own such an adapter.
    +
    + This support is also available as a module. If so, the module
    + will be called i2c-icy.
    +
    config I2C_MLXCPLD
    tristate "Mellanox I2C driver"
    depends on X86_64
    diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
    index a3245231b..d0e1c3d4e 100644
    --- a/drivers/i2c/busses/Makefile
    +++ b/drivers/i2c/busses/Makefile
    @@ -139,6 +139,7 @@ obj-$(CONFIG_I2C_BCM_KONA) += i2c-bcm-kona.o
    obj-$(CONFIG_I2C_BRCMSTB) += i2c-brcmstb.o
    obj-$(CONFIG_I2C_CROS_EC_TUNNEL) += i2c-cros-ec-tunnel.o
    obj-$(CONFIG_I2C_ELEKTOR) += i2c-elektor.o
    +obj-$(CONFIG_I2C_ICY) += i2c-icy.o
    obj-$(CONFIG_I2C_MLXCPLD) += i2c-mlxcpld.o
    obj-$(CONFIG_I2C_OPAL) += i2c-opal.o
    obj-$(CONFIG_I2C_PCA_ISA) += i2c-pca-isa.o
    diff --git a/drivers/i2c/busses/i2c-icy.c b/drivers/i2c/busses/i2c-icy.c
    new file mode 100644
    index 000000000..edac515da
    --- /dev/null
    +++ b/drivers/i2c/busses/i2c-icy.c
    @@ -0,0 +1,183 @@
    +// 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;
    + int val = z_readb(address);
    +
    + return val;
    +}
    +
    +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)
    +{
    + udelay(100);
    +}
    +
    +
    +
    +/*
    + * 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");
    --
    2.11.0
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      Last update: 2019-08-16 15:46    [W:4.082 / U:0.000 seconds]
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