xref: /openbmc/linux/drivers/base/platform-msi.c (revision a2cce7a9)
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 	return irq_domain_set_hwirq_and_chip(domain, virq, hwirq,
67 					     info->chip, info->chip_data);
68 }
69 #else
70 #define platform_msi_set_desc		NULL
71 #define platform_msi_init		NULL
72 #endif
73 
74 static void platform_msi_update_dom_ops(struct msi_domain_info *info)
75 {
76 	struct msi_domain_ops *ops = info->ops;
77 
78 	BUG_ON(!ops);
79 
80 	if (ops->msi_init == NULL)
81 		ops->msi_init = platform_msi_init;
82 	if (ops->set_desc == NULL)
83 		ops->set_desc = platform_msi_set_desc;
84 }
85 
86 static void platform_msi_write_msg(struct irq_data *data, struct msi_msg *msg)
87 {
88 	struct msi_desc *desc = irq_data_get_msi_desc(data);
89 	struct platform_msi_priv_data *priv_data;
90 
91 	priv_data = desc->platform.msi_priv_data;
92 
93 	priv_data->write_msg(desc, msg);
94 }
95 
96 static void platform_msi_update_chip_ops(struct msi_domain_info *info)
97 {
98 	struct irq_chip *chip = info->chip;
99 
100 	BUG_ON(!chip);
101 	if (!chip->irq_mask)
102 		chip->irq_mask = irq_chip_mask_parent;
103 	if (!chip->irq_unmask)
104 		chip->irq_unmask = irq_chip_unmask_parent;
105 	if (!chip->irq_eoi)
106 		chip->irq_eoi = irq_chip_eoi_parent;
107 	if (!chip->irq_set_affinity)
108 		chip->irq_set_affinity = msi_domain_set_affinity;
109 	if (!chip->irq_write_msi_msg)
110 		chip->irq_write_msi_msg = platform_msi_write_msg;
111 }
112 
113 static void platform_msi_free_descs(struct device *dev)
114 {
115 	struct msi_desc *desc, *tmp;
116 
117 	list_for_each_entry_safe(desc, tmp, dev_to_msi_list(dev), list) {
118 		list_del(&desc->list);
119 		free_msi_entry(desc);
120 	}
121 }
122 
123 static int platform_msi_alloc_descs(struct device *dev, int nvec,
124 				    struct platform_msi_priv_data *data)
125 
126 {
127 	int i;
128 
129 	for (i = 0; i < nvec; i++) {
130 		struct msi_desc *desc;
131 
132 		desc = alloc_msi_entry(dev);
133 		if (!desc)
134 			break;
135 
136 		desc->platform.msi_priv_data = data;
137 		desc->platform.msi_index = i;
138 		desc->nvec_used = 1;
139 
140 		list_add_tail(&desc->list, dev_to_msi_list(dev));
141 	}
142 
143 	if (i != nvec) {
144 		/* Clean up the mess */
145 		platform_msi_free_descs(dev);
146 
147 		return -ENOMEM;
148 	}
149 
150 	return 0;
151 }
152 
153 /**
154  * platform_msi_create_irq_domain - Create a platform MSI interrupt domain
155  * @np:		Optional device-tree node of the interrupt controller
156  * @info:	MSI domain info
157  * @parent:	Parent irq domain
158  *
159  * Updates the domain and chip ops and creates a platform MSI
160  * interrupt domain.
161  *
162  * Returns:
163  * A domain pointer or NULL in case of failure.
164  */
165 struct irq_domain *platform_msi_create_irq_domain(struct device_node *np,
166 						  struct msi_domain_info *info,
167 						  struct irq_domain *parent)
168 {
169 	struct irq_domain *domain;
170 
171 	if (info->flags & MSI_FLAG_USE_DEF_DOM_OPS)
172 		platform_msi_update_dom_ops(info);
173 	if (info->flags & MSI_FLAG_USE_DEF_CHIP_OPS)
174 		platform_msi_update_chip_ops(info);
175 
176 	domain = msi_create_irq_domain(np, info, parent);
177 	if (domain)
178 		domain->bus_token = DOMAIN_BUS_PLATFORM_MSI;
179 
180 	return domain;
181 }
182 
183 /**
184  * platform_msi_domain_alloc_irqs - Allocate MSI interrupts for @dev
185  * @dev:		The device for which to allocate interrupts
186  * @nvec:		The number of interrupts to allocate
187  * @write_msi_msg:	Callback to write an interrupt message for @dev
188  *
189  * Returns:
190  * Zero for success, or an error code in case of failure
191  */
192 int platform_msi_domain_alloc_irqs(struct device *dev, unsigned int nvec,
193 				   irq_write_msi_msg_t write_msi_msg)
194 {
195 	struct platform_msi_priv_data *priv_data;
196 	int err;
197 
198 	/*
199 	 * Limit the number of interrupts to 256 per device. Should we
200 	 * need to bump this up, DEV_ID_SHIFT should be adjusted
201 	 * accordingly (which would impact the max number of MSI
202 	 * capable devices).
203 	 */
204 	if (!dev->msi_domain || !write_msi_msg || !nvec ||
205 	    nvec > (1 << (32 - DEV_ID_SHIFT)))
206 		return -EINVAL;
207 
208 	if (dev->msi_domain->bus_token != DOMAIN_BUS_PLATFORM_MSI) {
209 		dev_err(dev, "Incompatible msi_domain, giving up\n");
210 		return -EINVAL;
211 	}
212 
213 	/* Already had a helping of MSI? Greed... */
214 	if (!list_empty(dev_to_msi_list(dev)))
215 		return -EBUSY;
216 
217 	priv_data = kzalloc(sizeof(*priv_data), GFP_KERNEL);
218 	if (!priv_data)
219 		return -ENOMEM;
220 
221 	priv_data->devid = ida_simple_get(&platform_msi_devid_ida,
222 					  0, 1 << DEV_ID_SHIFT, GFP_KERNEL);
223 	if (priv_data->devid < 0) {
224 		err = priv_data->devid;
225 		goto out_free_data;
226 	}
227 
228 	priv_data->write_msg = write_msi_msg;
229 
230 	err = platform_msi_alloc_descs(dev, nvec, priv_data);
231 	if (err)
232 		goto out_free_id;
233 
234 	err = msi_domain_alloc_irqs(dev->msi_domain, dev, nvec);
235 	if (err)
236 		goto out_free_desc;
237 
238 	return 0;
239 
240 out_free_desc:
241 	platform_msi_free_descs(dev);
242 out_free_id:
243 	ida_simple_remove(&platform_msi_devid_ida, priv_data->devid);
244 out_free_data:
245 	kfree(priv_data);
246 
247 	return err;
248 }
249 
250 /**
251  * platform_msi_domain_free_irqs - Free MSI interrupts for @dev
252  * @dev:	The device for which to free interrupts
253  */
254 void platform_msi_domain_free_irqs(struct device *dev)
255 {
256 	struct msi_desc *desc;
257 
258 	desc = first_msi_entry(dev);
259 	if (desc) {
260 		struct platform_msi_priv_data *data;
261 
262 		data = desc->platform.msi_priv_data;
263 
264 		ida_simple_remove(&platform_msi_devid_ida, data->devid);
265 		kfree(data);
266 	}
267 
268 	msi_domain_free_irqs(dev->msi_domain, dev);
269 	platform_msi_free_descs(dev);
270 }
271