xref: /openbmc/linux/include/misc/cxl.h (revision 1c2dd16a)
1 /*
2  * Copyright 2015 IBM Corp.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public License
6  * as published by the Free Software Foundation; either version
7  * 2 of the License, or (at your option) any later version.
8  */
9 
10 #ifndef _MISC_CXL_H
11 #define _MISC_CXL_H
12 
13 #include <linux/pci.h>
14 #include <linux/poll.h>
15 #include <linux/interrupt.h>
16 #include <uapi/misc/cxl.h>
17 
18 /*
19  * This documents the in kernel API for driver to use CXL. It allows kernel
20  * drivers to bind to AFUs using an AFU configuration record exposed as a PCI
21  * configuration record.
22  *
23  * This API enables control over AFU and contexts which can't be part of the
24  * generic PCI API. This API is agnostic to the actual AFU.
25  */
26 
27 #define CXL_SLOT_FLAG_DMA 0x1
28 
29 /*
30  * Checks if the given card is in a cxl capable slot. Pass CXL_SLOT_FLAG_DMA if
31  * the card requires CAPP DMA mode to also check if the system supports it.
32  * This is intended to be used by bi-modal devices to determine if they can use
33  * cxl mode or if they should continue running in PCI mode.
34  *
35  * Note that this only checks if the slot is cxl capable - it does not
36  * currently check if the CAPP is currently available for chips where it can be
37  * assigned to different PHBs on a first come first serve basis (i.e. P8)
38  */
39 bool cxl_slot_is_supported(struct pci_dev *dev, int flags);
40 
41 
42 #define CXL_BIMODE_CXL 1
43 #define CXL_BIMODE_PCI 2
44 
45 /*
46  * Check the mode that the given bi-modal CXL adapter is currently in and
47  * change it if necessary. This does not apply to AFU drivers.
48  *
49  * If the mode matches the requested mode this function will return 0 - if the
50  * driver was expecting the generic CXL driver to have bound to the adapter and
51  * it gets this return value it should fail the probe function to give the CXL
52  * driver a chance to probe it.
53  *
54  * If the mode does not match it will start a background task to unplug the
55  * device from Linux and switch its mode, and will return -EBUSY. At this
56  * point the calling driver should make sure it has released the device and
57  * fail its probe function.
58  *
59  * The offset of the CXL VSEC can be provided to this function. If 0 is passed,
60  * this function will search for a CXL VSEC with ID 0x1280 and return -ENODEV
61  * if it is not found.
62  */
63 #ifdef CONFIG_CXL_BIMODAL
64 int cxl_check_and_switch_mode(struct pci_dev *dev, int mode, int vsec);
65 #endif
66 
67 /* Get the AFU associated with a pci_dev */
68 struct cxl_afu *cxl_pci_to_afu(struct pci_dev *dev);
69 
70 /* Get the AFU conf record number associated with a pci_dev */
71 unsigned int cxl_pci_to_cfg_record(struct pci_dev *dev);
72 
73 
74 /*
75  * Context lifetime overview:
76  *
77  * An AFU context may be inited and then started and stoppped multiple times
78  * before it's released. ie.
79  *    - cxl_dev_context_init()
80  *      - cxl_start_context()
81  *      - cxl_stop_context()
82  *      - cxl_start_context()
83  *      - cxl_stop_context()
84  *     ...repeat...
85  *    - cxl_release_context()
86  * Once released, a context can't be started again.
87  *
88  * One context is inited by the cxl driver for every pci_dev. This is to be
89  * used as a default kernel context. cxl_get_context() will get this
90  * context. This context will be released by PCI hot unplug, so doesn't need to
91  * be released explicitly by drivers.
92  *
93  * Additional kernel contexts may be inited using cxl_dev_context_init().
94  * These must be released using cxl_context_detach().
95  *
96  * Once a context has been inited, IRQs may be configured. Firstly these IRQs
97  * must be allocated (cxl_allocate_afu_irqs()), then individually mapped to
98  * specific handlers (cxl_map_afu_irq()).
99  *
100  * These IRQs can be unmapped (cxl_unmap_afu_irq()) and finally released
101  * (cxl_free_afu_irqs()).
102  *
103  * The AFU can be reset (cxl_afu_reset()). This will cause the PSL/AFU
104  * hardware to lose track of all contexts. It's upto the caller of
105  * cxl_afu_reset() to restart these contexts.
106  */
107 
108 /*
109  * On pci_enabled_device(), the cxl driver will init a single cxl context for
110  * use by the driver. It doesn't start this context (as that will likely
111  * generate DMA traffic for most AFUs).
112  *
113  * This gets the default context associated with this pci_dev.  This context
114  * doesn't need to be released as this will be done by the PCI subsystem on hot
115  * unplug.
116  */
117 struct cxl_context *cxl_get_context(struct pci_dev *dev);
118 /*
119  * Allocate and initalise a context associated with a AFU PCI device. This
120  * doesn't start the context in the AFU.
121  */
122 struct cxl_context *cxl_dev_context_init(struct pci_dev *dev);
123 /*
124  * Release and free a context. Context should be stopped before calling.
125  */
126 int cxl_release_context(struct cxl_context *ctx);
127 
128 /*
129  * Set and get private data associated with a context. Allows drivers to have a
130  * back pointer to some useful structure.
131  */
132 int cxl_set_priv(struct cxl_context *ctx, void *priv);
133 void *cxl_get_priv(struct cxl_context *ctx);
134 
135 /*
136  * Allocate AFU interrupts for this context. num=0 will allocate the default
137  * for this AFU as given in the AFU descriptor. This number doesn't include the
138  * interrupt 0 (CAIA defines AFU IRQ 0 for page faults). Each interrupt to be
139  * used must map a handler with cxl_map_afu_irq.
140  */
141 int cxl_allocate_afu_irqs(struct cxl_context *cxl, int num);
142 /* Free allocated interrupts */
143 void cxl_free_afu_irqs(struct cxl_context *cxl);
144 
145 /*
146  * Map a handler for an AFU interrupt associated with a particular context. AFU
147  * IRQS numbers start from 1 (CAIA defines AFU IRQ 0 for page faults). cookie
148  * is private data is that will be provided to the interrupt handler.
149  */
150 int cxl_map_afu_irq(struct cxl_context *cxl, int num,
151 		    irq_handler_t handler, void *cookie, char *name);
152 /* unmap mapped IRQ handlers */
153 void cxl_unmap_afu_irq(struct cxl_context *cxl, int num, void *cookie);
154 
155 /*
156  * Start work on the AFU. This starts an cxl context and associates it with a
157  * task. task == NULL will make it a kernel context.
158  */
159 int cxl_start_context(struct cxl_context *ctx, u64 wed,
160 		      struct task_struct *task);
161 /*
162  * Stop a context and remove it from the PSL
163  */
164 int cxl_stop_context(struct cxl_context *ctx);
165 
166 /* Reset the AFU */
167 int cxl_afu_reset(struct cxl_context *ctx);
168 
169 /*
170  * Set a context as a master context.
171  * This sets the default problem space area mapped as the full space, rather
172  * than just the per context area (for slaves).
173  */
174 void cxl_set_master(struct cxl_context *ctx);
175 
176 /*
177  * Sets the context to use real mode memory accesses to operate with
178  * translation disabled. Note that this only makes sense for kernel contexts
179  * under bare metal, and will not work with virtualisation. May only be
180  * performed on stopped contexts.
181  */
182 int cxl_set_translation_mode(struct cxl_context *ctx, bool real_mode);
183 
184 /*
185  * Map and unmap the AFU Problem Space area. The amount and location mapped
186  * depends on if this context is a master or slave.
187  */
188 void __iomem *cxl_psa_map(struct cxl_context *ctx);
189 void cxl_psa_unmap(void __iomem *addr);
190 
191 /*  Get the process element for this context */
192 int cxl_process_element(struct cxl_context *ctx);
193 
194 /*
195  * Limit the number of interrupts that a single context can allocate via
196  * cxl_start_work. If using the api with a real phb, this may be used to
197  * request that additional default contexts be created when allocating
198  * interrupts via pci_enable_msix_range. These will be set to the same running
199  * state as the default context, and if that is running it will reuse the
200  * parameters previously passed to cxl_start_context for the default context.
201  */
202 int cxl_set_max_irqs_per_process(struct pci_dev *dev, int irqs);
203 int cxl_get_max_irqs_per_process(struct pci_dev *dev);
204 
205 /*
206  * Use to simultaneously iterate over hardware interrupt numbers, contexts and
207  * afu interrupt numbers allocated for the device via pci_enable_msix_range and
208  * is a useful convenience function when working with hardware that has
209  * limitations on the number of interrupts per process. *ctx and *afu_irq
210  * should be NULL and 0 to start the iteration.
211  */
212 int cxl_next_msi_hwirq(struct pci_dev *pdev, struct cxl_context **ctx, int *afu_irq);
213 
214 /*
215  * These calls allow drivers to create their own file descriptors and make them
216  * identical to the cxl file descriptor user API. An example use case:
217  *
218  * struct file_operations cxl_my_fops = {};
219  * ......
220  *	// Init the context
221  *	ctx = cxl_dev_context_init(dev);
222  *	if (IS_ERR(ctx))
223  *		return PTR_ERR(ctx);
224  *	// Create and attach a new file descriptor to my file ops
225  *	file = cxl_get_fd(ctx, &cxl_my_fops, &fd);
226  *	// Start context
227  *	rc = cxl_start_work(ctx, &work.work);
228  *	if (rc) {
229  *		fput(file);
230  *		put_unused_fd(fd);
231  *		return -ENODEV;
232  *	}
233  *	// No error paths after installing the fd
234  *	fd_install(fd, file);
235  *	return fd;
236  *
237  * This inits a context, and gets a file descriptor and associates some file
238  * ops to that file descriptor. If the file ops are blank, the cxl driver will
239  * fill them in with the default ones that mimic the standard user API.  Once
240  * completed, the file descriptor can be installed. Once the file descriptor is
241  * installed, it's visible to the user so no errors must occur past this point.
242  *
243  * If cxl_fd_release() file op call is installed, the context will be stopped
244  * and released when the fd is released. Hence the driver won't need to manage
245  * this itself.
246  */
247 
248 /*
249  * Take a context and associate it with my file ops. Returns the associated
250  * file and file descriptor. Any file ops which are blank are filled in by the
251  * cxl driver with the default ops to mimic the standard API.
252  */
253 struct file *cxl_get_fd(struct cxl_context *ctx, struct file_operations *fops,
254 			int *fd);
255 /* Get the context associated with this file */
256 struct cxl_context *cxl_fops_get_context(struct file *file);
257 /*
258  * Start a context associated a struct cxl_ioctl_start_work used by the
259  * standard cxl user API.
260  */
261 int cxl_start_work(struct cxl_context *ctx,
262 		   struct cxl_ioctl_start_work *work);
263 /*
264  * Export all the existing fops so drivers can use them
265  */
266 int cxl_fd_open(struct inode *inode, struct file *file);
267 int cxl_fd_release(struct inode *inode, struct file *file);
268 long cxl_fd_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
269 int cxl_fd_mmap(struct file *file, struct vm_area_struct *vm);
270 unsigned int cxl_fd_poll(struct file *file, struct poll_table_struct *poll);
271 ssize_t cxl_fd_read(struct file *file, char __user *buf, size_t count,
272 			   loff_t *off);
273 
274 /*
275  * For EEH, a driver may want to assert a PERST will reload the same image
276  * from flash into the FPGA.
277  *
278  * This is a property of the entire adapter, not a single AFU, so drivers
279  * should set this property with care!
280  */
281 void cxl_perst_reloads_same_image(struct cxl_afu *afu,
282 				  bool perst_reloads_same_image);
283 
284 /*
285  * Read the VPD for the card where the AFU resides
286  */
287 ssize_t cxl_read_adapter_vpd(struct pci_dev *dev, void *buf, size_t count);
288 
289 /*
290  * AFU driver ops allow an AFU driver to create their own events to pass to
291  * userspace through the file descriptor as a simpler alternative to overriding
292  * the read() and poll() calls that works with the generic cxl events. These
293  * events are given priority over the generic cxl events, so they will be
294  * delivered first if multiple types of events are pending.
295  *
296  * The AFU driver must call cxl_context_events_pending() to notify the cxl
297  * driver that new events are ready to be delivered for a specific context.
298  * cxl_context_events_pending() will adjust the current count of AFU driver
299  * events for this context, and wake up anyone waiting on the context wait
300  * queue.
301  *
302  * The cxl driver will then call fetch_event() to get a structure defining
303  * the size and address of the driver specific event data. The cxl driver
304  * will build a cxl header with type and process_element fields filled in,
305  * and header.size set to sizeof(struct cxl_event_header) + data_size.
306  * The total size of the event is limited to CXL_READ_MIN_SIZE (4K).
307  *
308  * fetch_event() is called with a spin lock held, so it must not sleep.
309  *
310  * The cxl driver will then deliver the event to userspace, and finally
311  * call event_delivered() to return the status of the operation, identified
312  * by cxl context and AFU driver event data pointers.
313  *   0        Success
314  *   -EFAULT  copy_to_user() has failed
315  *   -EINVAL  Event data pointer is NULL, or event size is greater than
316  *            CXL_READ_MIN_SIZE.
317  */
318 struct cxl_afu_driver_ops {
319 	struct cxl_event_afu_driver_reserved *(*fetch_event) (
320 						struct cxl_context *ctx);
321 	void (*event_delivered) (struct cxl_context *ctx,
322 				 struct cxl_event_afu_driver_reserved *event,
323 				 int rc);
324 };
325 
326 /*
327  * Associate the above driver ops with a specific context.
328  * Reset the current count of AFU driver events.
329  */
330 void cxl_set_driver_ops(struct cxl_context *ctx,
331 			struct cxl_afu_driver_ops *ops);
332 
333 /* Notify cxl driver that new events are ready to be delivered for context */
334 void cxl_context_events_pending(struct cxl_context *ctx,
335 				unsigned int new_events);
336 
337 #endif /* _MISC_CXL_H */
338