drivers/mux/mmio.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * MMIO register bitfield-controlled multiplexer driver
   4  *
   5  * Copyright (C) 2017 Pengutronix, Philipp Zabel <kernel@pengutronix.de>
   6  */
   7
   8 #include <linux/bitops.h>
   9 #include <linux/err.h>
  10 #include <linux/mfd/syscon.h>
  11 #include <linux/module.h>
  12 #include <linux/mux/driver.h>
  13 #include <linux/of.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/property.h>
  16 #include <linux/regmap.h>
  17
  18 static int mux_mmio_set(struct mux_control *mux, int state)
  19 {
  20         struct regmap_field **fields = mux_chip_priv(mux->chip);
  21
  22         return regmap_field_write(fields[mux_control_get_index(mux)], state);
  23 }
  24
  25 static const struct mux_control_ops mux_mmio_ops = {
  26         .set = mux_mmio_set,
  27 };
  28
  29 static const struct of_device_id mux_mmio_dt_ids[] = {
  30         { .compatible = "mmio-mux", },
  31         { .compatible = "reg-mux", },
  32         { /* sentinel */ }
  33 };
  34 MODULE_DEVICE_TABLE(of, mux_mmio_dt_ids);
  35
  36 static int mux_mmio_probe(struct platform_device *pdev)
  37 {
  38         struct device *dev = &pdev->dev;
  39         struct device_node *np = dev->of_node;
  40         struct regmap_field **fields;
  41         struct mux_chip *mux_chip;
  42         struct regmap *regmap;
  43         int num_fields;
  44         int ret;
  45         int i;
  46
  47         if (of_device_is_compatible(np, "mmio-mux")) {
  48                 regmap = syscon_node_to_regmap(np->parent);
  49         } else {
  50                 regmap = device_node_to_regmap(np);
  51                 /* Fallback to checking the parent node on "real" errors. */
  52                 if (IS_ERR(regmap) && regmap != ERR_PTR(-EPROBE_DEFER)) {
  53                         regmap = dev_get_regmap(dev->parent, NULL);
  54                         if (!regmap)
  55                                 regmap = ERR_PTR(-ENODEV);
  56                 }
  57         }
  58         if (IS_ERR(regmap))
  59                 return dev_err_probe(dev, PTR_ERR(regmap),
  60                                      "failed to get regmap\n");
  61
  62         ret = of_property_count_u32_elems(np, "mux-reg-masks");
  63         if (ret == 0 || ret % 2)
  64                 ret = -EINVAL;
  65         if (ret < 0) {
  66                 dev_err(dev, "mux-reg-masks property missing or invalid: %d\n",
  67                         ret);
  68                 return ret;
  69         }
  70         num_fields = ret / 2;
  71
  72         mux_chip = devm_mux_chip_alloc(dev, num_fields, num_fields *
  73                                        sizeof(*fields));
  74         if (IS_ERR(mux_chip))
  75                 return PTR_ERR(mux_chip);
  76
  77         fields = mux_chip_priv(mux_chip);
  78
  79         for (i = 0; i < num_fields; i++) {
  80                 struct mux_control *mux = &mux_chip->mux[i];
  81                 struct reg_field field;
  82                 s32 idle_state = MUX_IDLE_AS_IS;
  83                 u32 reg, mask;
  84                 int bits;
  85
  86                 ret = of_property_read_u32_index(np, "mux-reg-masks",
  87                                                  2 * i, &reg);
  88                 if (!ret)
  89                         ret = of_property_read_u32_index(np, "mux-reg-masks",
  90                                                          2 * i + 1, &mask);
  91                 if (ret < 0) {
  92                         dev_err(dev, "bitfield %d: failed to read mux-reg-masks property: %d\n",
  93                                 i, ret);
  94                         return ret;
  95                 }
  96
  97                 field.reg = reg;
  98                 field.msb = fls(mask) - 1;
  99                 field.lsb = ffs(mask) - 1;
 100
 101                 if (mask != GENMASK(field.msb, field.lsb)) {
 102                         dev_err(dev, "bitfield %d: invalid mask 0x%x\n",
 103                                 i, mask);
 104                         return -EINVAL;
 105                 }
 106
 107                 fields[i] = devm_regmap_field_alloc(dev, regmap, field);
 108                 if (IS_ERR(fields[i])) {
 109                         ret = PTR_ERR(fields[i]);
 110                         dev_err(dev, "bitfield %d: failed allocate: %d\n",
 111                                 i, ret);
 112                         return ret;
 113                 }
 114
 115                 bits = 1 + field.msb - field.lsb;
 116                 mux->states = 1 << bits;
 117
 118                 of_property_read_u32_index(np, "idle-states", i,
 119                                            (u32 *)&idle_state);
 120                 if (idle_state != MUX_IDLE_AS_IS) {
 121                         if (idle_state < 0 || idle_state >= mux->states) {
 122                                 dev_err(dev, "bitfield: %d: out of range idle state %d\n",
 123                                         i, idle_state);
 124                                 return -EINVAL;
 125                         }
 126
 127                         mux->idle_state = idle_state;
 128                 }
 129         }
 130
 131         mux_chip->ops = &mux_mmio_ops;
 132
 133         return devm_mux_chip_register(dev, mux_chip);
 134 }
 135
 136 static struct platform_driver mux_mmio_driver = {
 137         .driver = {
 138                 .name = "mmio-mux",
 139                 .of_match_table = mux_mmio_dt_ids,
 140         },
 141         .probe = mux_mmio_probe,
 142 };
 143 module_platform_driver(mux_mmio_driver);
 144
 145 MODULE_DESCRIPTION("MMIO register bitfield-controlled multiplexer driver");
 146 MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
 147 MODULE_LICENSE("GPL v2");