diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-icy.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-icy.c | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-icy.c b/drivers/i2c/busses/i2c-icy.c new file mode 100644 index 000000000000..8382eb64b424 --- /dev/null +++ b/drivers/i2c/busses/i2c-icy.c @@ -0,0 +1,230 @@ +// 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; + struct fwnode_handle *ltc2990_fwnode; + struct i2c_client *ltc2990_client; +}; + +/* + * 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 unsigned short const icy_ltc2990_addresses[] = { + 0x4c, 0x4d, 0x4e, 0x4f, I2C_CLIENT_END +}; + +/* + * Additional sensors exposed once this property is applied: + * + * in1 will be the voltage of the 5V rail, divided by 2. + * in2 will be the voltage of the 12V rail, divided by 4. + * temp3 will be measured using a PCB loop next the chip. + */ +static const u32 icy_ltc2990_meas_mode[] = {0, 3}; + +static const struct property_entry icy_ltc2990_props[] = { + PROPERTY_ENTRY_U32_ARRAY("lltc,meas-mode", icy_ltc2990_meas_mode), + { } +}; + +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; + struct fwnode_handle *new_fwnode; + struct i2c_board_info ltc2990_info = { + .type = "ltc2990", + .addr = 0x4c, + }; + + 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); + + /* + * The 2019 a1k.org PCBs have an LTC2990 at 0x4c, so start + * it automatically once ltc2990 is modprobed. + * + * in0 is the voltage of the internal 5V power supply. + * temp1 is the temperature inside the chip. + * + * See property_entry above for in1, in2, temp3. + */ + new_fwnode = fwnode_create_software_node(icy_ltc2990_props, NULL); + if (IS_ERR(new_fwnode)) { + dev_info(&z->dev, "Failed to create fwnode for LTC2990, error: %ld\n", + PTR_ERR(new_fwnode)); + } else { + /* + * Store the fwnode so we can destroy it on .remove(). + * Only store it on success, as fwnode_remove_software_node() + * is NULL safe, but not PTR_ERR safe. + */ + i2c->ltc2990_fwnode = new_fwnode; + ltc2990_info.fwnode = new_fwnode; + + i2c->ltc2990_client = + i2c_new_probed_device(&i2c->adapter, + <c2990_info, + icy_ltc2990_addresses, + NULL); + } + + return 0; +} + +static void icy_remove(struct zorro_dev *z) +{ + struct icy_i2c *i2c = dev_get_drvdata(&z->dev); + + i2c_unregister_device(i2c->ltc2990_client); + fwnode_remove_software_node(i2c->ltc2990_fwnode); + + 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"); |