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
devm_apple_tunable_parse(struct device * dev,struct device_node * np,const char * name,struct resource * res)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
apple_tunable_apply(void __iomem * regs,struct apple_tunable * tunable)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