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_platform.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 = dev_get_regmap(dev->parent, NULL) ?: ERR_PTR(-ENODEV);
  51         if (IS_ERR(regmap)) {
  52                 ret = PTR_ERR(regmap);
  53                 dev_err(dev, "failed to get regmap: %d\n", ret);
  54                 return ret;
  55         }
  56
  57         ret = of_property_count_u32_elems(np, "mux-reg-masks");
  58         if (ret == 0 || ret % 2)
  59                 ret = -EINVAL;
  60         if (ret < 0) {
  61                 dev_err(dev, "mux-reg-masks property missing or invalid: %d\n",
  62                         ret);
  63                 return ret;
  64         }
  65         num_fields = ret / 2;
  66
  67         mux_chip = devm_mux_chip_alloc(dev, num_fields, num_fields *
  68                                        sizeof(*fields));
  69         if (IS_ERR(mux_chip))
  70                 return PTR_ERR(mux_chip);
  71
  72         fields = mux_chip_priv(mux_chip);
  73
  74         for (i = 0; i < num_fields; i++) {
  75                 struct mux_control *mux = &mux_chip->mux[i];
  76                 struct reg_field field;
  77                 s32 idle_state = MUX_IDLE_AS_IS;
  78                 u32 reg, mask;
  79                 int bits;
  80
  81                 ret = of_property_read_u32_index(np, "mux-reg-masks",
  82                                                  2 * i, &reg);
  83                 if (!ret)
  84                         ret = of_property_read_u32_index(np, "mux-reg-masks",
  85                                                          2 * i + 1, &mask);
  86                 if (ret < 0) {
  87                         dev_err(dev, "bitfield %d: failed to read mux-reg-masks property: %d\n",
  88                                 i, ret);
  89                         return ret;
  90                 }
  91
  92                 field.reg = reg;
  93                 field.msb = fls(mask) - 1;
  94                 field.lsb = ffs(mask) - 1;
  95
  96                 if (mask != GENMASK(field.msb, field.lsb)) {
  97                         dev_err(dev, "bitfield %d: invalid mask 0x%x\n",
  98                                 i, mask);
  99                         return -EINVAL;
 100                 }
 101
 102                 fields[i] = devm_regmap_field_alloc(dev, regmap, field);
 103                 if (IS_ERR(fields[i])) {
 104                         ret = PTR_ERR(fields[i]);
 105                         dev_err(dev, "bitfield %d: failed allocate: %d\n",
 106                                 i, ret);
 107                         return ret;
 108                 }
 109
 110                 bits = 1 + field.msb - field.lsb;
 111                 mux->states = 1 << bits;
 112
 113                 of_property_read_u32_index(np, "idle-states", i,
 114                                            (u32 *)&idle_state);
 115                 if (idle_state != MUX_IDLE_AS_IS) {
 116                         if (idle_state < 0 || idle_state >= mux->states) {
 117                                 dev_err(dev, "bitfield: %d: out of range idle state %d\n",
 118                                         i, idle_state);
 119                                 return -EINVAL;
 120                         }
 121
 122                         mux->idle_state = idle_state;
 123                 }
 124         }
 125
 126         mux_chip->ops = &mux_mmio_ops;
 127
 128         return devm_mux_chip_register(dev, mux_chip);
 129 }
 130
 131 static struct platform_driver mux_mmio_driver = {
 132         .driver = {
 133                 .name = "mmio-mux",
 134                 .of_match_table = of_match_ptr(mux_mmio_dt_ids),
 135         },
 136         .probe = mux_mmio_probe,
 137 };
 138 module_platform_driver(mux_mmio_driver);
 139
 140 MODULE_DESCRIPTION("MMIO register bitfield-controlled multiplexer driver");
 141 MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
 142 MODULE_LICENSE("GPL v2");