1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Author: Sudeep Holla <sudeep.holla@arm.com>
4 * Copyright 2021 Arm Limited
5 *
6 * The PCC Address Space also referred as PCC Operation Region pertains to the
7 * region of PCC subspace that succeeds the PCC signature. The PCC Operation
8 * Region works in conjunction with the PCC Table(Platform Communications
9 * Channel Table). PCC subspaces that are marked for use as PCC Operation
10 * Regions must not be used as PCC subspaces for the standard ACPI features
11 * such as CPPC, RASF, PDTT and MPST. These standard features must always use
12 * the PCC Table instead.
13 *
14 * This driver sets up the PCC Address Space and installs an handler to enable
15 * handling of PCC OpRegion in the firmware.
16 *
17 */
18 #include <linux/kernel.h>
19 #include <linux/acpi.h>
20 #include <linux/completion.h>
21 #include <linux/idr.h>
22 #include <linux/io.h>
23
24 #include <acpi/pcc.h>
25
26 /*
27 * Arbitrary retries in case the remote processor is slow to respond
28 * to PCC commands
29 */
30 #define PCC_CMD_WAIT_RETRIES_NUM 500ULL
31
32 struct pcc_data {
33 struct pcc_mbox_chan *pcc_chan;
34 void __iomem *pcc_comm_addr;
35 struct completion done;
36 struct mbox_client cl;
37 struct acpi_pcc_info ctx;
38 };
39
40 static struct acpi_pcc_info pcc_ctx;
41
pcc_rx_callback(struct mbox_client * cl,void * m)42 static void pcc_rx_callback(struct mbox_client *cl, void *m)
43 {
44 struct pcc_data *data = container_of(cl, struct pcc_data, cl);
45
46 complete(&data->done);
47 }
48
49 static acpi_status
acpi_pcc_address_space_setup(acpi_handle region_handle,u32 function,void * handler_context,void ** region_context)50 acpi_pcc_address_space_setup(acpi_handle region_handle, u32 function,
51 void *handler_context, void **region_context)
52 {
53 struct pcc_data *data;
54 struct acpi_pcc_info *ctx = handler_context;
55 struct pcc_mbox_chan *pcc_chan;
56 static acpi_status ret;
57
58 data = kzalloc(sizeof(*data), GFP_KERNEL);
59 if (!data)
60 return AE_NO_MEMORY;
61
62 data->cl.rx_callback = pcc_rx_callback;
63 data->cl.knows_txdone = true;
64 data->ctx.length = ctx->length;
65 data->ctx.subspace_id = ctx->subspace_id;
66 data->ctx.internal_buffer = ctx->internal_buffer;
67
68 init_completion(&data->done);
69 data->pcc_chan = pcc_mbox_request_channel(&data->cl, ctx->subspace_id);
70 if (IS_ERR(data->pcc_chan)) {
71 pr_err("Failed to find PCC channel for subspace %d\n",
72 ctx->subspace_id);
73 ret = AE_NOT_FOUND;
74 goto err_free_data;
75 }
76
77 pcc_chan = data->pcc_chan;
78 if (!pcc_chan->mchan->mbox->txdone_irq) {
79 pr_err("This channel-%d does not support interrupt.\n",
80 ctx->subspace_id);
81 ret = AE_SUPPORT;
82 goto err_free_channel;
83 }
84 data->pcc_comm_addr = acpi_os_ioremap(pcc_chan->shmem_base_addr,
85 pcc_chan->shmem_size);
86 if (!data->pcc_comm_addr) {
87 pr_err("Failed to ioremap PCC comm region mem for %d\n",
88 ctx->subspace_id);
89 ret = AE_NO_MEMORY;
90 goto err_free_channel;
91 }
92
93 *region_context = data;
94 return AE_OK;
95
96 err_free_channel:
97 pcc_mbox_free_channel(data->pcc_chan);
98 err_free_data:
99 kfree(data);
100
101 return ret;
102 }
103
104 static acpi_status
acpi_pcc_address_space_handler(u32 function,acpi_physical_address addr,u32 bits,acpi_integer * value,void * handler_context,void * region_context)105 acpi_pcc_address_space_handler(u32 function, acpi_physical_address addr,
106 u32 bits, acpi_integer *value,
107 void *handler_context, void *region_context)
108 {
109 int ret;
110 struct pcc_data *data = region_context;
111 u64 usecs_lat;
112
113 reinit_completion(&data->done);
114
115 /* Write to Shared Memory */
116 memcpy_toio(data->pcc_comm_addr, (void *)value, data->ctx.length);
117
118 ret = mbox_send_message(data->pcc_chan->mchan, NULL);
119 if (ret < 0)
120 return AE_ERROR;
121
122 /*
123 * pcc_chan->latency is just a Nominal value. In reality the remote
124 * processor could be much slower to reply. So add an arbitrary
125 * amount of wait on top of Nominal.
126 */
127 usecs_lat = PCC_CMD_WAIT_RETRIES_NUM * data->pcc_chan->latency;
128 ret = wait_for_completion_timeout(&data->done,
129 usecs_to_jiffies(usecs_lat));
130 if (ret == 0) {
131 pr_err("PCC command executed timeout!\n");
132 return AE_TIME;
133 }
134
135 mbox_chan_txdone(data->pcc_chan->mchan, ret);
136
137 memcpy_fromio(value, data->pcc_comm_addr, data->ctx.length);
138
139 return AE_OK;
140 }
141
acpi_init_pcc(void)142 void __init acpi_init_pcc(void)
143 {
144 acpi_status status;
145
146 status = acpi_install_address_space_handler(ACPI_ROOT_OBJECT,
147 ACPI_ADR_SPACE_PLATFORM_COMM,
148 &acpi_pcc_address_space_handler,
149 &acpi_pcc_address_space_setup,
150 &pcc_ctx);
151 if (ACPI_FAILURE(status))
152 pr_alert("OperationRegion handler could not be installed\n");
153 }
154
