Alex Elder | e88afa5 | 2014-10-01 21:54:15 -0500 | [diff] [blame] | 1 | /* |
| 2 | * Greybus operations |
| 3 | * |
| 4 | * Copyright 2014 Google Inc. |
| 5 | * |
| 6 | * Released under the GPLv2 only. |
| 7 | */ |
| 8 | |
| 9 | #include <linux/kernel.h> |
| 10 | #include <linux/slab.h> |
| 11 | #include <linux/module.h> |
| 12 | #include <linux/workqueue.h> |
| 13 | |
| 14 | #include "greybus.h" |
| 15 | |
| 16 | /* |
| 17 | * All operation messages (both requests and responses) begin with |
| 18 | * a common header that encodes the size of the data (header |
| 19 | * included). This header also contains a unique identifier, which |
| 20 | * is used to keep track of in-flight operations. Finally, the |
| 21 | * header contains a operation type field, whose interpretation is |
| 22 | * dependent on what type of device lies on the other end of the |
| 23 | * connection. Response messages are distinguished from request |
| 24 | * messages by setting the high bit (0x80) in the operation type |
| 25 | * value. |
| 26 | * |
| 27 | * The wire format for all numeric fields in the header is little |
| 28 | * endian. Any operation-specific data begins immediately after the |
| 29 | * header, and is 64-bit aligned. |
| 30 | */ |
| 31 | struct gb_operation_msg_hdr { |
| 32 | __le16 size; /* Size in bytes of header + payload */ |
| 33 | __le16 id; /* Operation unique id */ |
| 34 | __u8 type; /* E.g GB_I2C_TYPE_* or GB_GPIO_TYPE_* */ |
| 35 | /* 3 bytes pad, must be zero (ignore when read) */ |
| 36 | } __aligned(sizeof(u64)); |
| 37 | |
| 38 | /* XXX Could be per-host device, per-module, or even per-connection */ |
| 39 | static DEFINE_SPINLOCK(gb_operations_lock); |
| 40 | |
| 41 | /* |
| 42 | * An operations's response message has arrived. If no callback was |
| 43 | * supplied it was submitted for asynchronous completion, so we notify |
| 44 | * any waiters. Otherwise we assume calling the completion is enough |
| 45 | * and nobody else will be waiting. |
| 46 | */ |
| 47 | void gb_operation_complete(struct gb_operation *operation) |
| 48 | { |
| 49 | if (operation->callback) |
| 50 | operation->callback(operation); |
| 51 | else |
| 52 | complete_all(&operation->completion); |
| 53 | } |
| 54 | |
| 55 | /* |
| 56 | * Wait for a submitted operatnoi to complete */ |
| 57 | int gb_operation_wait(struct gb_operation *operation) |
| 58 | { |
| 59 | int ret; |
| 60 | |
| 61 | ret = wait_for_completion_interruptible(&operation->completion); |
| 62 | /* If interrupted, cancel the in-flight buffer */ |
| 63 | if (ret < 0) |
| 64 | ret = greybus_kill_gbuf(operation->gbuf); |
| 65 | return ret; |
| 66 | |
| 67 | } |
| 68 | |
| 69 | /* |
| 70 | * Submit an outbound operation. The caller has filled in any |
| 71 | * payload so the request message is ready to go. If non-null, |
| 72 | * the callback function supplied will be called when the response |
| 73 | * message has arrived indicating the operation is complete. A null |
| 74 | * callback function is used for a synchronous request; return from |
| 75 | * this function won't occur until the operation is complete (or an |
| 76 | * interrupt occurs). |
| 77 | */ |
| 78 | int gb_operation_submit(struct gb_operation *operation, |
| 79 | gb_operation_callback callback) |
| 80 | { |
| 81 | int ret; |
| 82 | |
| 83 | /* XXX |
| 84 | * gfp is probably GFP_ATOMIC but really I think |
| 85 | * the gfp mask should go away. |
| 86 | */ |
| 87 | operation->callback = callback; |
| 88 | ret = greybus_submit_gbuf(operation->gbuf, GFP_KERNEL); |
| 89 | if (ret) |
| 90 | return ret; |
| 91 | if (!callback) |
| 92 | ret = gb_operation_wait(operation); |
| 93 | |
| 94 | return ret; |
| 95 | } |
| 96 | |
| 97 | /* |
| 98 | * Called when a greybus request message has actually been sent. |
| 99 | */ |
| 100 | static void gbuf_out_callback(struct gbuf *gbuf) |
| 101 | { |
| 102 | /* Record it's been submitted; need response now */ |
| 103 | } |
| 104 | |
| 105 | /* |
| 106 | * Create a Greybus operation having a buffer big enough for an |
| 107 | * outgoing payload of the given size to be sent over the given |
| 108 | * connection. |
| 109 | * |
| 110 | * Returns a pointer to the new operation or a null pointer if a |
| 111 | * failure occurs due to memory exhaustion. |
| 112 | */ |
| 113 | struct gb_operation *gb_operation_create(struct gb_connection *connection, |
| 114 | size_t size) |
| 115 | { |
| 116 | struct gb_operation *operation; |
| 117 | struct gb_operation_msg_hdr *header; |
| 118 | struct gbuf *gbuf; |
| 119 | |
| 120 | /* XXX Use a slab cache */ |
| 121 | operation = kzalloc(sizeof(*operation), GFP_KERNEL); |
| 122 | if (!operation) |
| 123 | return NULL; |
| 124 | |
| 125 | /* Our buffer holds a header in addition to the requested payload */ |
| 126 | size += sizeof(*header); |
Alex Elder | cd34507 | 2014-10-02 12:30:05 -0500 | [diff] [blame] | 127 | gbuf = greybus_alloc_gbuf(connection->interface->gmod, |
| 128 | connection->hd_cport_id, |
Alex Elder | e88afa5 | 2014-10-01 21:54:15 -0500 | [diff] [blame] | 129 | gbuf_out_callback, size, |
| 130 | GFP_KERNEL, operation); |
| 131 | if (gbuf) { |
| 132 | kfree(operation); |
| 133 | return NULL; |
| 134 | } |
| 135 | |
| 136 | operation->connection = connection; /* XXX refcount? */ |
| 137 | |
| 138 | /* Fill in the header structure and payload pointer */ |
| 139 | operation->gbuf = gbuf; |
| 140 | header = (struct gb_operation_msg_hdr *)&gbuf->transfer_buffer; |
| 141 | header->id = 0; |
Greg Kroah-Hartman | 322543a | 2014-10-02 21:25:21 -0700 | [diff] [blame^] | 142 | header->size = cpu_to_le16(size); |
Alex Elder | e88afa5 | 2014-10-01 21:54:15 -0500 | [diff] [blame] | 143 | operation->payload = (char *)header + sizeof(*header); |
| 144 | |
| 145 | operation->callback = NULL; /* set at submit time */ |
| 146 | init_completion(&operation->completion); |
| 147 | |
| 148 | spin_lock_irq(&gb_operations_lock); |
| 149 | list_add_tail(&operation->links, &connection->operations); |
| 150 | spin_unlock_irq(&gb_operations_lock); |
| 151 | |
| 152 | return operation; |
| 153 | } |
| 154 | |
| 155 | /* |
| 156 | * Destroy a previously created operation. |
| 157 | */ |
| 158 | void gb_operation_destroy(struct gb_operation *operation) |
| 159 | { |
| 160 | if (WARN_ON(!operation)) |
| 161 | return; |
| 162 | |
| 163 | /* XXX Make sure it's not in flight */ |
| 164 | spin_lock_irq(&gb_operations_lock); |
| 165 | list_del(&operation->links); |
| 166 | spin_unlock_irq(&gb_operations_lock); |
| 167 | |
| 168 | greybus_free_gbuf(operation->gbuf); |
| 169 | |
| 170 | kfree(operation); |
| 171 | } |