xref: /openbmc/linux/drivers/base/platform-msi.c (revision 3821a065)
1 /*
2  * MSI framework for platform devices
3  *
4  * Copyright (C) 2015 ARM Limited, All Rights Reserved.
5  * Author: Marc Zyngier <marc.zyngier@arm.com>
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
18  */
19 
20 #include <linux/device.h>
21 #include <linux/idr.h>
22 #include <linux/irq.h>
23 #include <linux/irqdomain.h>
24 #include <linux/msi.h>
25 #include <linux/slab.h>
26 
27 #define DEV_ID_SHIFT	24
28 
29 /*
30  * Internal data structure containing a (made up, but unique) devid
31  * and the callback to write the MSI message.
32  */
33 struct platform_msi_priv_data {
34 	irq_write_msi_msg_t	write_msg;
35 	int			devid;
36 };
37 
38 /* The devid allocator */
39 static DEFINE_IDA(platform_msi_devid_ida);
40 
41 #ifdef GENERIC_MSI_DOMAIN_OPS
42 /*
43  * Convert an msi_desc to a globaly unique identifier (per-device
44  * devid + msi_desc position in the msi_list).
45  */
46 static irq_hw_number_t platform_msi_calc_hwirq(struct msi_desc *desc)
47 {
48 	u32 devid;
49 
50 	devid = desc->platform.msi_priv_data->devid;
51 
52 	return (devid << (32 - DEV_ID_SHIFT)) | desc->platform.msi_index;
53 }
54 
55 static void platform_msi_set_desc(msi_alloc_info_t *arg, struct msi_desc *desc)
56 {
57 	arg->desc = desc;
58 	arg->hwirq = platform_msi_calc_hwirq(desc);
59 }
60 
61 static int platform_msi_init(struct irq_domain *domain,
62 			     struct msi_domain_info *info,
63 			     unsigned int virq, irq_hw_number_t hwirq,
64 			     msi_alloc_info_t *arg)
65 {
66 	struct irq_data *data;
67 
68 	irq_domain_set_hwirq_and_chip(domain, virq, hwirq,
69 				      info->chip, info->chip_data);
70 
71 	/*
72 	 * Save the MSI descriptor in handler_data so that the
73 	 * irq_write_msi_msg callback can retrieve it (and the
74 	 * associated device).
75 	 */
76 	data = irq_domain_get_irq_data(domain, virq);
77 	data->handler_data = arg->desc;
78 
79 	return 0;
80 }
81 #else
82 #define platform_msi_set_desc		NULL
83 #define platform_msi_init		NULL
84 #endif
85 
86 static void platform_msi_update_dom_ops(struct msi_domain_info *info)
87 {
88 	struct msi_domain_ops *ops = info->ops;
89 
90 	BUG_ON(!ops);
91 
92 	if (ops->msi_init == NULL)
93 		ops->msi_init = platform_msi_init;
94 	if (ops->set_desc == NULL)
95 		ops->set_desc = platform_msi_set_desc;
96 }
97 
98 static void platform_msi_write_msg(struct irq_data *data, struct msi_msg *msg)
99 {
100 	struct msi_desc *desc = irq_data_get_irq_handler_data(data);
101 	struct platform_msi_priv_data *priv_data;
102 
103 	priv_data = desc->platform.msi_priv_data;
104 
105 	priv_data->write_msg(desc, msg);
106 }
107 
108 static void platform_msi_update_chip_ops(struct msi_domain_info *info)
109 {
110 	struct irq_chip *chip = info->chip;
111 
112 	BUG_ON(!chip);
113 	if (!chip->irq_mask)
114 		chip->irq_mask = irq_chip_mask_parent;
115 	if (!chip->irq_unmask)
116 		chip->irq_unmask = irq_chip_unmask_parent;
117 	if (!chip->irq_eoi)
118 		chip->irq_eoi = irq_chip_eoi_parent;
119 	if (!chip->irq_set_affinity)
120 		chip->irq_set_affinity = msi_domain_set_affinity;
121 	if (!chip->irq_write_msi_msg)
122 		chip->irq_write_msi_msg = platform_msi_write_msg;
123 }
124 
125 static void platform_msi_free_descs(struct device *dev)
126 {
127 	struct msi_desc *desc, *tmp;
128 
129 	list_for_each_entry_safe(desc, tmp, dev_to_msi_list(dev), list) {
130 		list_del(&desc->list);
131 		free_msi_entry(desc);
132 	}
133 }
134 
135 static int platform_msi_alloc_descs(struct device *dev, int nvec,
136 				    struct platform_msi_priv_data *data)
137 
138 {
139 	int i;
140 
141 	for (i = 0; i < nvec; i++) {
142 		struct msi_desc *desc;
143 
144 		desc = alloc_msi_entry(dev);
145 		if (!desc)
146 			break;
147 
148 		desc->platform.msi_priv_data = data;
149 		desc->platform.msi_index = i;
150 		desc->nvec_used = 1;
151 
152 		list_add_tail(&desc->list, dev_to_msi_list(dev));
153 	}
154 
155 	if (i != nvec) {
156 		/* Clean up the mess */
157 		platform_msi_free_descs(dev);
158 
159 		return -ENOMEM;
160 	}
161 
162 	return 0;
163 }
164 
165 /**
166  * platform_msi_create_irq_domain - Create a platform MSI interrupt domain
167  * @np:		Optional device-tree node of the interrupt controller
168  * @info:	MSI domain info
169  * @parent:	Parent irq domain
170  *
171  * Updates the domain and chip ops and creates a platform MSI
172  * interrupt domain.
173  *
174  * Returns:
175  * A domain pointer or NULL in case of failure.
176  */
177 struct irq_domain *platform_msi_create_irq_domain(struct device_node *np,
178 						  struct msi_domain_info *info,
179 						  struct irq_domain *parent)
180 {
181 	struct irq_domain *domain;
182 
183 	if (info->flags & MSI_FLAG_USE_DEF_DOM_OPS)
184 		platform_msi_update_dom_ops(info);
185 	if (info->flags & MSI_FLAG_USE_DEF_CHIP_OPS)
186 		platform_msi_update_chip_ops(info);
187 
188 	domain = msi_create_irq_domain(np, info, parent);
189 	if (domain)
190 		domain->bus_token = DOMAIN_BUS_PLATFORM_MSI;
191 
192 	return domain;
193 }
194 
195 /**
196  * platform_msi_domain_alloc_irqs - Allocate MSI interrupts for @dev
197  * @dev:		The device for which to allocate interrupts
198  * @nvec:		The number of interrupts to allocate
199  * @write_msi_msg:	Callback to write an interrupt message for @dev
200  *
201  * Returns:
202  * Zero for success, or an error code in case of failure
203  */
204 int platform_msi_domain_alloc_irqs(struct device *dev, unsigned int nvec,
205 				   irq_write_msi_msg_t write_msi_msg)
206 {
207 	struct platform_msi_priv_data *priv_data;
208 	int err;
209 
210 	/*
211 	 * Limit the number of interrupts to 256 per device. Should we
212 	 * need to bump this up, DEV_ID_SHIFT should be adjusted
213 	 * accordingly (which would impact the max number of MSI
214 	 * capable devices).
215 	 */
216 	if (!dev->msi_domain || !write_msi_msg || !nvec ||
217 	    nvec > (1 << (32 - DEV_ID_SHIFT)))
218 		return -EINVAL;
219 
220 	if (dev->msi_domain->bus_token != DOMAIN_BUS_PLATFORM_MSI) {
221 		dev_err(dev, "Incompatible msi_domain, giving up\n");
222 		return -EINVAL;
223 	}
224 
225 	/* Already had a helping of MSI? Greed... */
226 	if (!list_empty(dev_to_msi_list(dev)))
227 		return -EBUSY;
228 
229 	priv_data = kzalloc(sizeof(*priv_data), GFP_KERNEL);
230 	if (!priv_data)
231 		return -ENOMEM;
232 
233 	priv_data->devid = ida_simple_get(&platform_msi_devid_ida,
234 					  0, 1 << DEV_ID_SHIFT, GFP_KERNEL);
235 	if (priv_data->devid < 0) {
236 		err = priv_data->devid;
237 		goto out_free_data;
238 	}
239 
240 	priv_data->write_msg = write_msi_msg;
241 
242 	err = platform_msi_alloc_descs(dev, nvec, priv_data);
243 	if (err)
244 		goto out_free_id;
245 
246 	err = msi_domain_alloc_irqs(dev->msi_domain, dev, nvec);
247 	if (err)
248 		goto out_free_desc;
249 
250 	return 0;
251 
252 out_free_desc:
253 	platform_msi_free_descs(dev);
254 out_free_id:
255 	ida_simple_remove(&platform_msi_devid_ida, priv_data->devid);
256 out_free_data:
257 	kfree(priv_data);
258 
259 	return err;
260 }
261 
262 /**
263  * platform_msi_domain_free_irqs - Free MSI interrupts for @dev
264  * @dev:	The device for which to free interrupts
265  */
266 void platform_msi_domain_free_irqs(struct device *dev)
267 {
268 	struct msi_desc *desc;
269 
270 	desc = first_msi_entry(dev);
271 	if (desc) {
272 		struct platform_msi_priv_data *data;
273 
274 		data = desc->platform.msi_priv_data;
275 
276 		ida_simple_remove(&platform_msi_devid_ida, data->devid);
277 		kfree(data);
278 	}
279 
280 	msi_domain_free_irqs(dev->msi_domain, dev);
281 	platform_msi_free_descs(dev);
282 }
283