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, ®); 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"); 148