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         { /* sentinel */ }
  32 };
  33 MODULE_DEVICE_TABLE(of, mux_mmio_dt_ids);
  34
  35 static int mux_mmio_probe(struct platform_device *pdev)
  36 {
  37         struct device *dev = &pdev->dev;
  38         struct device_node *np = dev->of_node;
  39         struct regmap_field **fields;
  40         struct mux_chip *mux_chip;
  41         struct regmap *regmap;
  42         int num_fields;
  43         int ret;
  44         int i;
  45
  46         regmap = syscon_node_to_regmap(np->parent);
  47         if (IS_ERR(regmap)) {
  48                 ret = PTR_ERR(regmap);
  49                 dev_err(dev, "failed to get regmap: %d\n", ret);
  50                 return ret;
  51         }
  52
  53         ret = of_property_count_u32_elems(np, "mux-reg-masks");
  54         if (ret == 0 || ret % 2)
  55                 ret = -EINVAL;
  56         if (ret < 0) {
  57                 dev_err(dev, "mux-reg-masks property missing or invalid: %d\n",
  58                         ret);
  59                 return ret;
  60         }
  61         num_fields = ret / 2;
  62
  63         mux_chip = devm_mux_chip_alloc(dev, num_fields, num_fields *
  64                                        sizeof(*fields));
  65         if (IS_ERR(mux_chip))
  66                 return PTR_ERR(mux_chip);
  67
  68         fields = mux_chip_priv(mux_chip);
  69
  70         for (i = 0; i < num_fields; i++) {
  71                 struct mux_control *mux = &mux_chip->mux[i];
  72                 struct reg_field field;
  73                 s32 idle_state = MUX_IDLE_AS_IS;
  74                 u32 reg, mask;
  75                 int bits;
  76
  77                 ret = of_property_read_u32_index(np, "mux-reg-masks",
  78                                                  2 * i, &reg);
  79                 if (!ret)
  80                         ret = of_property_read_u32_index(np, "mux-reg-masks",
  81                                                          2 * i + 1, &mask);
  82                 if (ret < 0) {
  83                         dev_err(dev, "bitfield %d: failed to read mux-reg-masks property: %d\n",
  84                                 i, ret);
  85                         return ret;
  86                 }
  87
  88                 field.reg = reg;
  89                 field.msb = fls(mask) - 1;
  90                 field.lsb = ffs(mask) - 1;
  91
  92                 if (mask != GENMASK(field.msb, field.lsb)) {
  93                         dev_err(dev, "bitfield %d: invalid mask 0x%x\n",
  94                                 i, mask);
  95                         return -EINVAL;
  96                 }
  97
  98                 fields[i] = devm_regmap_field_alloc(dev, regmap, field);
  99                 if (IS_ERR(fields[i])) {
 100                         ret = PTR_ERR(fields[i]);
 101                         dev_err(dev, "bitfield %d: failed allocate: %d\n",
 102                                 i, ret);
 103                         return ret;
 104                 }
 105
 106                 bits = 1 + field.msb - field.lsb;
 107                 mux->states = 1 << bits;
 108
 109                 of_property_read_u32_index(np, "idle-states", i,
 110                                            (u32 *)&idle_state);
 111                 if (idle_state != MUX_IDLE_AS_IS) {
 112                         if (idle_state < 0 || idle_state >= mux->states) {
 113                                 dev_err(dev, "bitfield: %d: out of range idle state %d\n",
 114                                         i, idle_state);
 115                                 return -EINVAL;
 116                         }
 117
 118                         mux->idle_state = idle_state;
 119                 }
 120         }
 121
 122         mux_chip->ops = &mux_mmio_ops;
 123
 124         return devm_mux_chip_register(dev, mux_chip);
 125 }
 126
 127 static struct platform_driver mux_mmio_driver = {
 128         .driver = {
 129                 .name = "mmio-mux",
 130                 .of_match_table = of_match_ptr(mux_mmio_dt_ids),
 131         },
 132         .probe = mux_mmio_probe,
 133 };
 134 module_platform_driver(mux_mmio_driver);
 135
 136 MODULE_DESCRIPTION("MMIO register bitfield-controlled multiplexer driver");
 137 MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
 138 MODULE_LICENSE("GPL v2");