1 // SPDX-License-Identifier: GPL-2.0-only OR MIT 2 /* 3 * Apple Silicon hardware tunable support 4 * 5 * Each tunable is a list with each entry containing a offset into the MMIO 6 * region, a mask of bits to be cleared and a set of bits to be set. These 7 * tunables are passed along by the previous boot stages and vary from device 8 * to device such that they cannot be hardcoded in the individual drivers. 9 * 10 * Copyright (C) The Asahi Linux Contributors 11 */ 12 13 #include <linux/io.h> 14 #include <linux/module.h> 15 #include <linux/of.h> 16 #include <linux/overflow.h> 17 #include <linux/soc/apple/tunable.h> 18 19 struct apple_tunable *devm_apple_tunable_parse(struct device *dev, 20 struct device_node *np, 21 const char *name, 22 struct resource *res) 23 { 24 struct apple_tunable *tunable; 25 struct property *prop; 26 const __be32 *p; 27 size_t sz; 28 int i; 29 30 if (resource_size(res) < 4) 31 return ERR_PTR(-EINVAL); 32 33 prop = of_find_property(np, name, NULL); 34 if (!prop) 35 return ERR_PTR(-ENOENT); 36 37 if (prop->length % (3 * sizeof(u32))) 38 return ERR_PTR(-EINVAL); 39 sz = prop->length / (3 * sizeof(u32)); 40 41 tunable = devm_kzalloc(dev, struct_size(tunable, values, sz), GFP_KERNEL); 42 if (!tunable) 43 return ERR_PTR(-ENOMEM); 44 tunable->sz = sz; 45 46 for (i = 0, p = NULL; i < tunable->sz; ++i) { 47 p = of_prop_next_u32(prop, p, &tunable->values[i].offset); 48 p = of_prop_next_u32(prop, p, &tunable->values[i].mask); 49 p = of_prop_next_u32(prop, p, &tunable->values[i].value); 50 51 /* Sanity checks to catch bugs in our bootloader */ 52 if (tunable->values[i].offset % 4) 53 return ERR_PTR(-EINVAL); 54 if (tunable->values[i].offset > (resource_size(res) - 4)) 55 return ERR_PTR(-EINVAL); 56 } 57 58 return tunable; 59 } 60 EXPORT_SYMBOL(devm_apple_tunable_parse); 61 62 void apple_tunable_apply(void __iomem *regs, struct apple_tunable *tunable) 63 { 64 size_t i; 65 66 for (i = 0; i < tunable->sz; ++i) { 67 u32 val, old_val; 68 69 old_val = readl(regs + tunable->values[i].offset); 70 val = old_val & ~tunable->values[i].mask; 71 val |= tunable->values[i].value; 72 if (val != old_val) 73 writel(val, regs + tunable->values[i].offset); 74 } 75 } 76 EXPORT_SYMBOL(apple_tunable_apply); 77 78 MODULE_LICENSE("Dual MIT/GPL"); 79 MODULE_AUTHOR("Sven Peter <sven@kernel.org>"); 80 MODULE_DESCRIPTION("Apple Silicon hardware tunable support"); 81