drivers/mux/mmio.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * MMIO register bitfield-controlled multiplexer driver
0004  *
0005  * Copyright (C) 2017 Pengutronix, Philipp Zabel <kernel@pengutronix.de>
0006  */
0007
0008 #include <linux/bitops.h>
0009 #include <linux/err.h>
0010 #include <linux/mfd/syscon.h>
0011 #include <linux/module.h>
0012 #include <linux/mux/driver.h>
0013 #include <linux/of_platform.h>
0014 #include <linux/platform_device.h>
0015 #include <linux/property.h>
0016 #include <linux/regmap.h>
0017
0018 static int mux_mmio_set(struct mux_control *mux, int state)
0019 {
0020     struct regmap_field **fields = mux_chip_priv(mux->chip);
0021
0022     return regmap_field_write(fields[mux_control_get_index(mux)], state);
0023 }
0024
0025 static const struct mux_control_ops mux_mmio_ops = {
0026     .set = mux_mmio_set,
0027 };
0028
0029 static const struct of_device_id mux_mmio_dt_ids[] = {
0030     { .compatible = "mmio-mux", },
0031     { .compatible = "reg-mux", },
0032     { /* sentinel */ }
0033 };
0034 MODULE_DEVICE_TABLE(of, mux_mmio_dt_ids);
0035
0036 static int mux_mmio_probe(struct platform_device *pdev)
0037 {
0038     struct device *dev = &pdev->dev;
0039     struct device_node *np = dev->of_node;
0040     struct regmap_field **fields;
0041     struct mux_chip *mux_chip;
0042     struct regmap *regmap;
0043     int num_fields;
0044     int ret;
0045     int i;
0046
0047     if (of_device_is_compatible(np, "mmio-mux"))
0048         regmap = syscon_node_to_regmap(np->parent);
0049     else
0050         regmap = dev_get_regmap(dev->parent, NULL) ?: ERR_PTR(-ENODEV);
0051     if (IS_ERR(regmap)) {
0052         ret = PTR_ERR(regmap);
0053         dev_err(dev, "failed to get regmap: %d\n", ret);
0054         return ret;
0055     }
0056
0057     ret = of_property_count_u32_elems(np, "mux-reg-masks");
0058     if (ret == 0 || ret % 2)
0059         ret = -EINVAL;
0060     if (ret < 0) {
0061         dev_err(dev, "mux-reg-masks property missing or invalid: %d\n",
0062             ret);
0063         return ret;
0064     }
0065     num_fields = ret / 2;
0066
0067     mux_chip = devm_mux_chip_alloc(dev, num_fields, num_fields *
0068                        sizeof(*fields));
0069     if (IS_ERR(mux_chip))
0070         return PTR_ERR(mux_chip);
0071
0072     fields = mux_chip_priv(mux_chip);
0073
0074     for (i = 0; i < num_fields; i++) {
0075         struct mux_control *mux = &mux_chip->mux[i];
0076         struct reg_field field;
0077         s32 idle_state = MUX_IDLE_AS_IS;
0078         u32 reg, mask;
0079         int bits;
0080
0081         ret = of_property_read_u32_index(np, "mux-reg-masks",
0082                          2 * i, &reg);
0083         if (!ret)
0084             ret = of_property_read_u32_index(np, "mux-reg-masks",
0085                              2 * i + 1, &mask);
0086         if (ret < 0) {
0087             dev_err(dev, "bitfield %d: failed to read mux-reg-masks property: %d\n",
0088                 i, ret);
0089             return ret;
0090         }
0091
0092         field.reg = reg;
0093         field.msb = fls(mask) - 1;
0094         field.lsb = ffs(mask) - 1;
0095
0096         if (mask != GENMASK(field.msb, field.lsb)) {
0097             dev_err(dev, "bitfield %d: invalid mask 0x%x\n",
0098                 i, mask);
0099             return -EINVAL;
0100         }
0101
0102         fields[i] = devm_regmap_field_alloc(dev, regmap, field);
0103         if (IS_ERR(fields[i])) {
0104             ret = PTR_ERR(fields[i]);
0105             dev_err(dev, "bitfield %d: failed allocate: %d\n",
0106                 i, ret);
0107             return ret;
0108         }
0109
0110         bits = 1 + field.msb - field.lsb;
0111         mux->states = 1 << bits;
0112
0113         of_property_read_u32_index(np, "idle-states", i,
0114                        (u32 *)&idle_state);
0115         if (idle_state != MUX_IDLE_AS_IS) {
0116             if (idle_state < 0 || idle_state >= mux->states) {
0117                 dev_err(dev, "bitfield: %d: out of range idle state %d\n",
0118                     i, idle_state);
0119                 return -EINVAL;
0120             }
0121
0122             mux->idle_state = idle_state;
0123         }
0124     }
0125
0126     mux_chip->ops = &mux_mmio_ops;
0127
0128     return devm_mux_chip_register(dev, mux_chip);
0129 }
0130
0131 static struct platform_driver mux_mmio_driver = {
0132     .driver = {
0133         .name = "mmio-mux",
0134         .of_match_table = of_match_ptr(mux_mmio_dt_ids),
0135     },
0136     .probe = mux_mmio_probe,
0137 };
0138 module_platform_driver(mux_mmio_driver);
0139
0140 MODULE_DESCRIPTION("MMIO register bitfield-controlled multiplexer driver");
0141 MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
0142 MODULE_LICENSE("GPL v2");