1 /*
2  * Remote processor machine-specific module for DA8XX
3  *
4  * Copyright (C) 2013 Texas Instruments, Inc.
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * version 2 as published by the Free Software Foundation.
9  */
10 
11 #include <linux/bitops.h>
12 #include <linux/clk.h>
13 #include <linux/err.h>
14 #include <linux/interrupt.h>
15 #include <linux/io.h>
16 #include <linux/irq.h>
17 #include <linux/kernel.h>
18 #include <linux/module.h>
19 #include <linux/platform_device.h>
20 #include <linux/remoteproc.h>
21 
22 #include <mach/clock.h>   /* for davinci_clk_reset_assert/deassert() */
23 
24 #include "remoteproc_internal.h"
25 
26 static char *da8xx_fw_name;
27 module_param(da8xx_fw_name, charp, S_IRUGO);
28 MODULE_PARM_DESC(da8xx_fw_name,
29 		 "Name of DSP firmware file in /lib/firmware (if not specified defaults to 'rproc-dsp-fw')");
30 
31 /*
32  * OMAP-L138 Technical References:
33  * http://www.ti.com/product/omap-l138
34  */
35 #define SYSCFG_CHIPSIG0 BIT(0)
36 #define SYSCFG_CHIPSIG1 BIT(1)
37 #define SYSCFG_CHIPSIG2 BIT(2)
38 #define SYSCFG_CHIPSIG3 BIT(3)
39 #define SYSCFG_CHIPSIG4 BIT(4)
40 
41 /**
42  * struct da8xx_rproc - da8xx remote processor instance state
43  * @rproc: rproc handle
44  * @dsp_clk: placeholder for platform's DSP clk
45  * @ack_fxn: chip-specific ack function for ack'ing irq
46  * @irq_data: ack_fxn function parameter
47  * @chipsig: virt ptr to DSP interrupt registers (CHIPSIG & CHIPSIG_CLR)
48  * @bootreg: virt ptr to DSP boot address register (HOST1CFG)
49  * @irq: irq # used by this instance
50  */
51 struct da8xx_rproc {
52 	struct rproc *rproc;
53 	struct clk *dsp_clk;
54 	void (*ack_fxn)(struct irq_data *data);
55 	struct irq_data *irq_data;
56 	void __iomem *chipsig;
57 	void __iomem *bootreg;
58 	int irq;
59 };
60 
61 /**
62  * handle_event() - inbound virtqueue message workqueue function
63  *
64  * This function is registered as a kernel thread and is scheduled by the
65  * kernel handler.
66  */
67 static irqreturn_t handle_event(int irq, void *p)
68 {
69 	struct rproc *rproc = (struct rproc *)p;
70 
71 	/* Process incoming buffers on all our vrings */
72 	rproc_vq_interrupt(rproc, 0);
73 	rproc_vq_interrupt(rproc, 1);
74 
75 	return IRQ_HANDLED;
76 }
77 
78 /**
79  * da8xx_rproc_callback() - inbound virtqueue message handler
80  *
81  * This handler is invoked directly by the kernel whenever the remote
82  * core (DSP) has modified the state of a virtqueue.  There is no
83  * "payload" message indicating the virtqueue index as is the case with
84  * mailbox-based implementations on OMAP4.  As such, this handler "polls"
85  * each known virtqueue index for every invocation.
86  */
87 static irqreturn_t da8xx_rproc_callback(int irq, void *p)
88 {
89 	struct rproc *rproc = (struct rproc *)p;
90 	struct da8xx_rproc *drproc = (struct da8xx_rproc *)rproc->priv;
91 	u32 chipsig;
92 
93 	chipsig = readl(drproc->chipsig);
94 	if (chipsig & SYSCFG_CHIPSIG0) {
95 		/* Clear interrupt level source */
96 		writel(SYSCFG_CHIPSIG0, drproc->chipsig + 4);
97 
98 		/*
99 		 * ACK intr to AINTC.
100 		 *
101 		 * It has already been ack'ed by the kernel before calling
102 		 * this function, but since the ARM<->DSP interrupts in the
103 		 * CHIPSIG register are "level" instead of "pulse" variety,
104 		 * we need to ack it after taking down the level else we'll
105 		 * be called again immediately after returning.
106 		 */
107 		drproc->ack_fxn(drproc->irq_data);
108 
109 		return IRQ_WAKE_THREAD;
110 	}
111 
112 	return IRQ_HANDLED;
113 }
114 
115 static int da8xx_rproc_start(struct rproc *rproc)
116 {
117 	struct device *dev = rproc->dev.parent;
118 	struct da8xx_rproc *drproc = (struct da8xx_rproc *)rproc->priv;
119 	struct clk *dsp_clk = drproc->dsp_clk;
120 
121 	/* hw requires the start (boot) address be on 1KB boundary */
122 	if (rproc->bootaddr & 0x3ff) {
123 		dev_err(dev, "invalid boot address: must be aligned to 1KB\n");
124 
125 		return -EINVAL;
126 	}
127 
128 	writel(rproc->bootaddr, drproc->bootreg);
129 
130 	clk_enable(dsp_clk);
131 	davinci_clk_reset_deassert(dsp_clk);
132 
133 	return 0;
134 }
135 
136 static int da8xx_rproc_stop(struct rproc *rproc)
137 {
138 	struct da8xx_rproc *drproc = rproc->priv;
139 
140 	clk_disable(drproc->dsp_clk);
141 
142 	return 0;
143 }
144 
145 /* kick a virtqueue */
146 static void da8xx_rproc_kick(struct rproc *rproc, int vqid)
147 {
148 	struct da8xx_rproc *drproc = (struct da8xx_rproc *)rproc->priv;
149 
150 	/* Interrupt remote proc */
151 	writel(SYSCFG_CHIPSIG2, drproc->chipsig);
152 }
153 
154 static const struct rproc_ops da8xx_rproc_ops = {
155 	.start = da8xx_rproc_start,
156 	.stop = da8xx_rproc_stop,
157 	.kick = da8xx_rproc_kick,
158 };
159 
160 static int reset_assert(struct device *dev)
161 {
162 	struct clk *dsp_clk;
163 
164 	dsp_clk = clk_get(dev, NULL);
165 	if (IS_ERR(dsp_clk)) {
166 		dev_err(dev, "clk_get error: %ld\n", PTR_ERR(dsp_clk));
167 		return PTR_ERR(dsp_clk);
168 	}
169 
170 	davinci_clk_reset_assert(dsp_clk);
171 	clk_put(dsp_clk);
172 
173 	return 0;
174 }
175 
176 static int da8xx_rproc_probe(struct platform_device *pdev)
177 {
178 	struct device *dev = &pdev->dev;
179 	struct da8xx_rproc *drproc;
180 	struct rproc *rproc;
181 	struct irq_data *irq_data;
182 	struct resource *bootreg_res;
183 	struct resource *chipsig_res;
184 	struct clk *dsp_clk;
185 	void __iomem *chipsig;
186 	void __iomem *bootreg;
187 	int irq;
188 	int ret;
189 
190 	irq = platform_get_irq(pdev, 0);
191 	if (irq < 0) {
192 		dev_err(dev, "platform_get_irq(pdev, 0) error: %d\n", irq);
193 		return irq;
194 	}
195 
196 	irq_data = irq_get_irq_data(irq);
197 	if (!irq_data) {
198 		dev_err(dev, "irq_get_irq_data(%d): NULL\n", irq);
199 		return -EINVAL;
200 	}
201 
202 	bootreg_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
203 	bootreg = devm_ioremap_resource(dev, bootreg_res);
204 	if (IS_ERR(bootreg))
205 		return PTR_ERR(bootreg);
206 
207 	chipsig_res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
208 	chipsig = devm_ioremap_resource(dev, chipsig_res);
209 	if (IS_ERR(chipsig))
210 		return PTR_ERR(chipsig);
211 
212 	dsp_clk = devm_clk_get(dev, NULL);
213 	if (IS_ERR(dsp_clk)) {
214 		dev_err(dev, "clk_get error: %ld\n", PTR_ERR(dsp_clk));
215 
216 		return PTR_ERR(dsp_clk);
217 	}
218 
219 	rproc = rproc_alloc(dev, "dsp", &da8xx_rproc_ops, da8xx_fw_name,
220 		sizeof(*drproc));
221 	if (!rproc)
222 		return -ENOMEM;
223 
224 	drproc = rproc->priv;
225 	drproc->rproc = rproc;
226 	rproc->has_iommu = false;
227 
228 	platform_set_drvdata(pdev, rproc);
229 
230 	/* everything the ISR needs is now setup, so hook it up */
231 	ret = devm_request_threaded_irq(dev, irq, da8xx_rproc_callback,
232 					handle_event, 0, "da8xx-remoteproc",
233 					rproc);
234 	if (ret) {
235 		dev_err(dev, "devm_request_threaded_irq error: %d\n", ret);
236 		goto free_rproc;
237 	}
238 
239 	/*
240 	 * rproc_add() can end up enabling the DSP's clk with the DSP
241 	 * *not* in reset, but da8xx_rproc_start() needs the DSP to be
242 	 * held in reset at the time it is called.
243 	 */
244 	ret = reset_assert(dev);
245 	if (ret)
246 		goto free_rproc;
247 
248 	drproc->chipsig = chipsig;
249 	drproc->bootreg = bootreg;
250 	drproc->ack_fxn = irq_data->chip->irq_ack;
251 	drproc->irq_data = irq_data;
252 	drproc->irq = irq;
253 	drproc->dsp_clk = dsp_clk;
254 
255 	ret = rproc_add(rproc);
256 	if (ret) {
257 		dev_err(dev, "rproc_add failed: %d\n", ret);
258 		goto free_rproc;
259 	}
260 
261 	return 0;
262 
263 free_rproc:
264 	rproc_free(rproc);
265 
266 	return ret;
267 }
268 
269 static int da8xx_rproc_remove(struct platform_device *pdev)
270 {
271 	struct device *dev = &pdev->dev;
272 	struct rproc *rproc = platform_get_drvdata(pdev);
273 	struct da8xx_rproc *drproc = (struct da8xx_rproc *)rproc->priv;
274 
275 	/*
276 	 * It's important to place the DSP in reset before going away,
277 	 * since a subsequent insmod of this module may enable the DSP's
278 	 * clock before its program/boot-address has been loaded and
279 	 * before this module's probe has had a chance to reset the DSP.
280 	 * Without the reset, the DSP can lockup permanently when it
281 	 * begins executing garbage.
282 	 */
283 	reset_assert(dev);
284 
285 	/*
286 	 * The devm subsystem might end up releasing things before
287 	 * freeing the irq, thus allowing an interrupt to sneak in while
288 	 * the device is being removed.  This should prevent that.
289 	 */
290 	disable_irq(drproc->irq);
291 
292 	rproc_del(rproc);
293 	rproc_free(rproc);
294 
295 	return 0;
296 }
297 
298 static struct platform_driver da8xx_rproc_driver = {
299 	.probe = da8xx_rproc_probe,
300 	.remove = da8xx_rproc_remove,
301 	.driver = {
302 		.name = "davinci-rproc",
303 	},
304 };
305 
306 module_platform_driver(da8xx_rproc_driver);
307 
308 MODULE_LICENSE("GPL v2");
309 MODULE_DESCRIPTION("DA8XX Remote Processor control driver");
310