1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * PolarFire SoC (MPFS) Peripheral Clock Reset Controller 4 * 5 * Author: Conor Dooley <conor.dooley@microchip.com> 6 * Copyright (c) 2022 Microchip Technology Inc. and its subsidiaries. 7 * 8 */ 9 #include <linux/auxiliary_bus.h> 10 #include <linux/delay.h> 11 #include <linux/module.h> 12 #include <linux/platform_device.h> 13 #include <linux/reset-controller.h> 14 #include <dt-bindings/clock/microchip,mpfs-clock.h> 15 #include <soc/microchip/mpfs.h> 16 17 /* 18 * The ENVM reset is the lowest bit in the register & I am using the CLK_FOO 19 * defines in the dt to make things easier to configure - so this is accounting 20 * for the offset of 3 there. 21 */ 22 #define MPFS_PERIPH_OFFSET CLK_ENVM 23 #define MPFS_NUM_RESETS 30u 24 #define MPFS_SLEEP_MIN_US 100 25 #define MPFS_SLEEP_MAX_US 200 26 27 /* block concurrent access to the soft reset register */ 28 static DEFINE_SPINLOCK(mpfs_reset_lock); 29 30 /* 31 * Peripheral clock resets 32 */ 33 34 static int mpfs_assert(struct reset_controller_dev *rcdev, unsigned long id) 35 { 36 unsigned long flags; 37 u32 reg; 38 39 spin_lock_irqsave(&mpfs_reset_lock, flags); 40 41 reg = mpfs_reset_read(rcdev->dev); 42 reg |= BIT(id); 43 mpfs_reset_write(rcdev->dev, reg); 44 45 spin_unlock_irqrestore(&mpfs_reset_lock, flags); 46 47 return 0; 48 } 49 50 static int mpfs_deassert(struct reset_controller_dev *rcdev, unsigned long id) 51 { 52 unsigned long flags; 53 u32 reg; 54 55 spin_lock_irqsave(&mpfs_reset_lock, flags); 56 57 reg = mpfs_reset_read(rcdev->dev); 58 reg &= ~BIT(id); 59 mpfs_reset_write(rcdev->dev, reg); 60 61 spin_unlock_irqrestore(&mpfs_reset_lock, flags); 62 63 return 0; 64 } 65 66 static int mpfs_status(struct reset_controller_dev *rcdev, unsigned long id) 67 { 68 u32 reg = mpfs_reset_read(rcdev->dev); 69 70 /* 71 * It is safe to return here as MPFS_NUM_RESETS makes sure the sign bit 72 * is never hit. 73 */ 74 return (reg & BIT(id)); 75 } 76 77 static int mpfs_reset(struct reset_controller_dev *rcdev, unsigned long id) 78 { 79 mpfs_assert(rcdev, id); 80 81 usleep_range(MPFS_SLEEP_MIN_US, MPFS_SLEEP_MAX_US); 82 83 mpfs_deassert(rcdev, id); 84 85 return 0; 86 } 87 88 static const struct reset_control_ops mpfs_reset_ops = { 89 .reset = mpfs_reset, 90 .assert = mpfs_assert, 91 .deassert = mpfs_deassert, 92 .status = mpfs_status, 93 }; 94 95 static int mpfs_reset_xlate(struct reset_controller_dev *rcdev, 96 const struct of_phandle_args *reset_spec) 97 { 98 unsigned int index = reset_spec->args[0]; 99 100 /* 101 * CLK_RESERVED does not map to a clock, but it does map to a reset, 102 * so it has to be accounted for here. It is the reset for the fabric, 103 * so if this reset gets called - do not reset it. 104 */ 105 if (index == CLK_RESERVED) { 106 dev_err(rcdev->dev, "Resetting the fabric is not supported\n"); 107 return -EINVAL; 108 } 109 110 if (index < MPFS_PERIPH_OFFSET || index >= (MPFS_PERIPH_OFFSET + rcdev->nr_resets)) { 111 dev_err(rcdev->dev, "Invalid reset index %u\n", index); 112 return -EINVAL; 113 } 114 115 return index - MPFS_PERIPH_OFFSET; 116 } 117 118 static int mpfs_reset_probe(struct auxiliary_device *adev, 119 const struct auxiliary_device_id *id) 120 { 121 struct device *dev = &adev->dev; 122 struct reset_controller_dev *rcdev; 123 124 rcdev = devm_kzalloc(dev, sizeof(*rcdev), GFP_KERNEL); 125 if (!rcdev) 126 return -ENOMEM; 127 128 rcdev->dev = dev; 129 rcdev->dev->parent = dev->parent; 130 rcdev->ops = &mpfs_reset_ops; 131 rcdev->of_node = dev->parent->of_node; 132 rcdev->of_reset_n_cells = 1; 133 rcdev->of_xlate = mpfs_reset_xlate; 134 rcdev->nr_resets = MPFS_NUM_RESETS; 135 136 return devm_reset_controller_register(dev, rcdev); 137 } 138 139 static const struct auxiliary_device_id mpfs_reset_ids[] = { 140 { 141 .name = "clk_mpfs.reset-mpfs", 142 }, 143 { } 144 }; 145 MODULE_DEVICE_TABLE(auxiliary, mpfs_reset_ids); 146 147 static struct auxiliary_driver mpfs_reset_driver = { 148 .probe = mpfs_reset_probe, 149 .id_table = mpfs_reset_ids, 150 }; 151 152 module_auxiliary_driver(mpfs_reset_driver); 153 154 MODULE_DESCRIPTION("Microchip PolarFire SoC Reset Driver"); 155 MODULE_AUTHOR("Conor Dooley <conor.dooley@microchip.com>"); 156 MODULE_IMPORT_NS(MCHP_CLK_MPFS); 157