xref: /linux/drivers/acpi/riscv/cppc.c (revision f61389a9cd26b424485acade726ccfff96c749de)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Implement CPPC FFH helper routines for RISC-V.
4  *
5  * Copyright (C) 2024 Ventana Micro Systems Inc.
6  */
7 
8 #include <acpi/cppc_acpi.h>
9 #include <asm/csr.h>
10 #include <asm/sbi.h>
11 
12 #define SBI_EXT_CPPC 0x43505043
13 
14 /* CPPC interfaces defined in SBI spec */
15 #define SBI_CPPC_PROBE			0x0
16 #define SBI_CPPC_READ			0x1
17 #define SBI_CPPC_READ_HI		0x2
18 #define SBI_CPPC_WRITE			0x3
19 
20 /* RISC-V FFH definitions from RISC-V FFH spec */
21 #define FFH_CPPC_TYPE(r)		(((r) & GENMASK_ULL(63, 60)) >> 60)
22 #define FFH_CPPC_SBI_REG(r)		((r) & GENMASK(31, 0))
23 #define FFH_CPPC_CSR_NUM(r)		((r) & GENMASK(11, 0))
24 
25 #define FFH_CPPC_SBI			0x1
26 #define FFH_CPPC_CSR			0x2
27 
28 struct sbi_cppc_data {
29 	u64 val;
30 	u32 reg;
31 	struct sbiret ret;
32 };
33 
34 static bool cppc_ext_present;
35 
sbi_cppc_init(void)36 static int __init sbi_cppc_init(void)
37 {
38 	if (sbi_spec_version >= sbi_mk_version(2, 0) &&
39 	    sbi_probe_extension(SBI_EXT_CPPC) > 0) {
40 		cppc_ext_present = true;
41 	} else {
42 		cppc_ext_present = false;
43 	}
44 
45 	return 0;
46 }
47 device_initcall(sbi_cppc_init);
48 
sbi_cppc_read(void * read_data)49 static void sbi_cppc_read(void *read_data)
50 {
51 	struct sbi_cppc_data *data = (struct sbi_cppc_data *)read_data;
52 
53 	data->ret = sbi_ecall(SBI_EXT_CPPC, SBI_CPPC_READ,
54 			      data->reg, 0, 0, 0, 0, 0);
55 }
56 
sbi_cppc_write(void * write_data)57 static void sbi_cppc_write(void *write_data)
58 {
59 	struct sbi_cppc_data *data = (struct sbi_cppc_data *)write_data;
60 
61 	data->ret = sbi_ecall(SBI_EXT_CPPC, SBI_CPPC_WRITE,
62 			      data->reg, data->val, 0, 0, 0, 0);
63 }
64 
cppc_ffh_csr_read(void * read_data)65 static void cppc_ffh_csr_read(void *read_data)
66 {
67 	struct sbi_cppc_data *data = (struct sbi_cppc_data *)read_data;
68 
69 	switch (data->reg) {
70 	/* Support only TIME CSR for now */
71 	case CSR_TIME:
72 		data->ret.value = csr_read(CSR_TIME);
73 		data->ret.error = 0;
74 		break;
75 	default:
76 		data->ret.error = -EINVAL;
77 		break;
78 	}
79 }
80 
cppc_ffh_csr_write(void * write_data)81 static void cppc_ffh_csr_write(void *write_data)
82 {
83 	struct sbi_cppc_data *data = (struct sbi_cppc_data *)write_data;
84 
85 	data->ret.error = -EINVAL;
86 }
87 
88 /*
89  * Refer to drivers/acpi/cppc_acpi.c for the description of the functions
90  * below.
91  */
cpc_ffh_supported(void)92 bool cpc_ffh_supported(void)
93 {
94 	return true;
95 }
96 
cpc_read_ffh(int cpu,struct cpc_reg * reg,u64 * val)97 int cpc_read_ffh(int cpu, struct cpc_reg *reg, u64 *val)
98 {
99 	struct sbi_cppc_data data;
100 
101 	if (WARN_ON_ONCE(irqs_disabled()))
102 		return -EPERM;
103 
104 	if (FFH_CPPC_TYPE(reg->address) == FFH_CPPC_SBI) {
105 		if (!cppc_ext_present)
106 			return -EINVAL;
107 
108 		data.reg = FFH_CPPC_SBI_REG(reg->address);
109 
110 		smp_call_function_single(cpu, sbi_cppc_read, &data, 1);
111 
112 		*val = data.ret.value;
113 
114 		return (data.ret.error) ? sbi_err_map_linux_errno(data.ret.error) : 0;
115 	} else if (FFH_CPPC_TYPE(reg->address) == FFH_CPPC_CSR) {
116 		data.reg = FFH_CPPC_CSR_NUM(reg->address);
117 
118 		smp_call_function_single(cpu, cppc_ffh_csr_read, &data, 1);
119 
120 		*val = data.ret.value;
121 
122 		return (data.ret.error) ? sbi_err_map_linux_errno(data.ret.error) : 0;
123 	}
124 
125 	return -EINVAL;
126 }
127 
cpc_write_ffh(int cpu,struct cpc_reg * reg,u64 val)128 int cpc_write_ffh(int cpu, struct cpc_reg *reg, u64 val)
129 {
130 	struct sbi_cppc_data data;
131 
132 	if (WARN_ON_ONCE(irqs_disabled()))
133 		return -EPERM;
134 
135 	if (FFH_CPPC_TYPE(reg->address) == FFH_CPPC_SBI) {
136 		if (!cppc_ext_present)
137 			return -EINVAL;
138 
139 		data.reg = FFH_CPPC_SBI_REG(reg->address);
140 		data.val = val;
141 
142 		smp_call_function_single(cpu, sbi_cppc_write, &data, 1);
143 
144 		return (data.ret.error) ? sbi_err_map_linux_errno(data.ret.error) : 0;
145 	} else if (FFH_CPPC_TYPE(reg->address) == FFH_CPPC_CSR) {
146 		data.reg = FFH_CPPC_CSR_NUM(reg->address);
147 		data.val = val;
148 
149 		smp_call_function_single(cpu, cppc_ffh_csr_write, &data, 1);
150 
151 		return (data.ret.error) ? sbi_err_map_linux_errno(data.ret.error) : 0;
152 	}
153 
154 	return -EINVAL;
155 }
156