diff options
Diffstat (limited to 'drivers/i2c/muxes/i2c-mux-reg.c')
-rw-r--r-- | drivers/i2c/muxes/i2c-mux-reg.c | 290 |
1 files changed, 290 insertions, 0 deletions
diff --git a/drivers/i2c/muxes/i2c-mux-reg.c b/drivers/i2c/muxes/i2c-mux-reg.c new file mode 100644 index 000000000..5fbd5bd08 --- /dev/null +++ b/drivers/i2c/muxes/i2c-mux-reg.c @@ -0,0 +1,290 @@ +/* + * I2C multiplexer using a single register + * + * Copyright 2015 Freescale Semiconductor + * York Sun <yorksun@freescale.com> + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. + */ + +#include <linux/i2c.h> +#include <linux/i2c-mux.h> +#include <linux/init.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/of_address.h> +#include <linux/platform_data/i2c-mux-reg.h> +#include <linux/platform_device.h> +#include <linux/slab.h> + +struct regmux { + struct i2c_adapter *parent; + struct i2c_adapter **adap; /* child busses */ + struct i2c_mux_reg_platform_data data; +}; + +static int i2c_mux_reg_set(const struct regmux *mux, unsigned int chan_id) +{ + if (!mux->data.reg) + return -EINVAL; + + /* + * Write to the register, followed by a read to ensure the write is + * completed on a "posted" bus, for example PCI or write buffers. + * The endianness of reading doesn't matter and the return data + * is not used. + */ + switch (mux->data.reg_size) { + case 4: + if (mux->data.little_endian) + iowrite32(chan_id, mux->data.reg); + else + iowrite32be(chan_id, mux->data.reg); + if (!mux->data.write_only) + ioread32(mux->data.reg); + break; + case 2: + if (mux->data.little_endian) + iowrite16(chan_id, mux->data.reg); + else + iowrite16be(chan_id, mux->data.reg); + if (!mux->data.write_only) + ioread16(mux->data.reg); + break; + case 1: + iowrite8(chan_id, mux->data.reg); + if (!mux->data.write_only) + ioread8(mux->data.reg); + break; + } + + return 0; +} + +static int i2c_mux_reg_select(struct i2c_adapter *adap, void *data, + unsigned int chan) +{ + struct regmux *mux = data; + + return i2c_mux_reg_set(mux, chan); +} + +static int i2c_mux_reg_deselect(struct i2c_adapter *adap, void *data, + unsigned int chan) +{ + struct regmux *mux = data; + + if (mux->data.idle_in_use) + return i2c_mux_reg_set(mux, mux->data.idle); + + return 0; +} + +#ifdef CONFIG_OF +static int i2c_mux_reg_probe_dt(struct regmux *mux, + struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + struct device_node *adapter_np, *child; + struct i2c_adapter *adapter; + struct resource res; + unsigned *values; + int i = 0; + + if (!np) + return -ENODEV; + + adapter_np = of_parse_phandle(np, "i2c-parent", 0); + if (!adapter_np) { + dev_err(&pdev->dev, "Cannot parse i2c-parent\n"); + return -ENODEV; + } + adapter = of_find_i2c_adapter_by_node(adapter_np); + of_node_put(adapter_np); + if (!adapter) + return -EPROBE_DEFER; + + mux->parent = adapter; + mux->data.parent = i2c_adapter_id(adapter); + put_device(&adapter->dev); + + mux->data.n_values = of_get_child_count(np); + if (of_find_property(np, "little-endian", NULL)) { + mux->data.little_endian = true; + } else if (of_find_property(np, "big-endian", NULL)) { + mux->data.little_endian = false; + } else { +#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : \ + defined(__LITTLE_ENDIAN) + mux->data.little_endian = true; +#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : \ + defined(__BIG_ENDIAN) + mux->data.little_endian = false; +#else +#error Endianness not defined? +#endif + } + if (of_find_property(np, "write-only", NULL)) + mux->data.write_only = true; + else + mux->data.write_only = false; + + values = devm_kzalloc(&pdev->dev, + sizeof(*mux->data.values) * mux->data.n_values, + GFP_KERNEL); + if (!values) { + dev_err(&pdev->dev, "Cannot allocate values array"); + return -ENOMEM; + } + + for_each_child_of_node(np, child) { + of_property_read_u32(child, "reg", values + i); + i++; + } + mux->data.values = values; + + if (!of_property_read_u32(np, "idle-state", &mux->data.idle)) + mux->data.idle_in_use = true; + + /* map address from "reg" if exists */ + if (of_address_to_resource(np, 0, &res)) { + mux->data.reg_size = resource_size(&res); + mux->data.reg = devm_ioremap_resource(&pdev->dev, &res); + if (IS_ERR(mux->data.reg)) + return PTR_ERR(mux->data.reg); + } + + return 0; +} +#else +static int i2c_mux_reg_probe_dt(struct regmux *mux, + struct platform_device *pdev) +{ + return 0; +} +#endif + +static int i2c_mux_reg_probe(struct platform_device *pdev) +{ + struct regmux *mux; + struct i2c_adapter *parent; + struct resource *res; + int (*deselect)(struct i2c_adapter *, void *, u32); + unsigned int class; + int i, ret, nr; + + mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL); + if (!mux) + return -ENOMEM; + + platform_set_drvdata(pdev, mux); + + if (dev_get_platdata(&pdev->dev)) { + memcpy(&mux->data, dev_get_platdata(&pdev->dev), + sizeof(mux->data)); + + parent = i2c_get_adapter(mux->data.parent); + if (!parent) + return -EPROBE_DEFER; + + mux->parent = parent; + } else { + ret = i2c_mux_reg_probe_dt(mux, pdev); + if (ret < 0) { + dev_err(&pdev->dev, "Error parsing device tree"); + return ret; + } + } + + if (!mux->data.reg) { + dev_info(&pdev->dev, + "Register not set, using platform resource\n"); + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + mux->data.reg_size = resource_size(res); + mux->data.reg = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(mux->data.reg)) + return PTR_ERR(mux->data.reg); + } + + if (mux->data.reg_size != 4 && mux->data.reg_size != 2 && + mux->data.reg_size != 1) { + dev_err(&pdev->dev, "Invalid register size\n"); + return -EINVAL; + } + + mux->adap = devm_kzalloc(&pdev->dev, + sizeof(*mux->adap) * mux->data.n_values, + GFP_KERNEL); + if (!mux->adap) { + dev_err(&pdev->dev, "Cannot allocate i2c_adapter structure"); + return -ENOMEM; + } + + if (mux->data.idle_in_use) + deselect = i2c_mux_reg_deselect; + else + deselect = NULL; + + for (i = 0; i < mux->data.n_values; i++) { + nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0; + class = mux->data.classes ? mux->data.classes[i] : 0; + + mux->adap[i] = i2c_add_mux_adapter(mux->parent, &pdev->dev, mux, + nr, mux->data.values[i], + class, i2c_mux_reg_select, + deselect); + if (!mux->adap[i]) { + ret = -ENODEV; + dev_err(&pdev->dev, "Failed to add adapter %d\n", i); + goto add_adapter_failed; + } + } + + dev_dbg(&pdev->dev, "%d port mux on %s adapter\n", + mux->data.n_values, mux->parent->name); + + return 0; + +add_adapter_failed: + for (; i > 0; i--) + i2c_del_mux_adapter(mux->adap[i - 1]); + + return ret; +} + +static int i2c_mux_reg_remove(struct platform_device *pdev) +{ + struct regmux *mux = platform_get_drvdata(pdev); + int i; + + for (i = 0; i < mux->data.n_values; i++) + i2c_del_mux_adapter(mux->adap[i]); + + i2c_put_adapter(mux->parent); + + return 0; +} + +static const struct of_device_id i2c_mux_reg_of_match[] = { + { .compatible = "i2c-mux-reg", }, + {}, +}; +MODULE_DEVICE_TABLE(of, i2c_mux_reg_of_match); + +static struct platform_driver i2c_mux_reg_driver = { + .probe = i2c_mux_reg_probe, + .remove = i2c_mux_reg_remove, + .driver = { + .name = "i2c-mux-reg", + }, +}; + +module_platform_driver(i2c_mux_reg_driver); + +MODULE_DESCRIPTION("Register-based I2C multiplexer driver"); +MODULE_AUTHOR("York Sun <yorksun@freescale.com>"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:i2c-mux-reg"); |