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 		 "\n\t\tName of DSP firmware file in /lib/firmware"
30 		 " (if not specified defaults to 'rproc-dsp-fw')");
31 
32 /*
33  * OMAP-L138 Technical References:
34  * http://www.ti.com/product/omap-l138
35  */
36 #define SYSCFG_CHIPSIG0 BIT(0)
37 #define SYSCFG_CHIPSIG1 BIT(1)
38 #define SYSCFG_CHIPSIG2 BIT(2)
39 #define SYSCFG_CHIPSIG3 BIT(3)
40 #define SYSCFG_CHIPSIG4 BIT(4)
41 
42 /**
43  * struct da8xx_rproc - da8xx remote processor instance state
44  * @rproc: rproc handle
45  * @dsp_clk: placeholder for platform's DSP clk
46  * @ack_fxn: chip-specific ack function for ack'ing irq
47  * @irq_data: ack_fxn function parameter
48  * @chipsig: virt ptr to DSP interrupt registers (CHIPSIG & CHIPSIG_CLR)
49  * @bootreg: virt ptr to DSP boot address register (HOST1CFG)
50  * @irq: irq # used by this instance
51  */
52 struct da8xx_rproc {
53 	struct rproc *rproc;
54 	struct clk *dsp_clk;
55 	void (*ack_fxn)(struct irq_data *data);
56 	struct irq_data *irq_data;
57 	void __iomem *chipsig;
58 	void __iomem *bootreg;
59 	int irq;
60 };
61 
62 /**
63  * handle_event() - inbound virtqueue message workqueue function
64  *
65  * This function is registered as a kernel thread and is scheduled by the
66  * kernel handler.
67  */
68 static irqreturn_t handle_event(int irq, void *p)
69 {
70 	struct rproc *rproc = (struct rproc *)p;
71 
72 	/* Process incoming buffers on all our vrings */
73 	rproc_vq_interrupt(rproc, 0);
74 	rproc_vq_interrupt(rproc, 1);
75 
76 	return IRQ_HANDLED;
77 }
78 
79 /**
80  * da8xx_rproc_callback() - inbound virtqueue message handler
81  *
82  * This handler is invoked directly by the kernel whenever the remote
83  * core (DSP) has modified the state of a virtqueue.  There is no
84  * "payload" message indicating the virtqueue index as is the case with
85  * mailbox-based implementations on OMAP4.  As such, this handler "polls"
86  * each known virtqueue index for every invocation.
87  */
88 static irqreturn_t da8xx_rproc_callback(int irq, void *p)
89 {
90 	struct rproc *rproc = (struct rproc *)p;
91 	struct da8xx_rproc *drproc = (struct da8xx_rproc *)rproc->priv;
92 	u32 chipsig;
93 
94 	chipsig = readl(drproc->chipsig);
95 	if (chipsig & SYSCFG_CHIPSIG0) {
96 		/* Clear interrupt level source */
97 		writel(SYSCFG_CHIPSIG0, drproc->chipsig + 4);
98 
99 		/*
100 		 * ACK intr to AINTC.
101 		 *
102 		 * It has already been ack'ed by the kernel before calling
103 		 * this function, but since the ARM<->DSP interrupts in the
104 		 * CHIPSIG register are "level" instead of "pulse" variety,
105 		 * we need to ack it after taking down the level else we'll
106 		 * be called again immediately after returning.
107 		 */
108 		drproc->ack_fxn(drproc->irq_data);
109 
110 		return IRQ_WAKE_THREAD;
111 	}
112 
113 	return IRQ_HANDLED;
114 }
115 
116 static int da8xx_rproc_start(struct rproc *rproc)
117 {
118 	struct device *dev = rproc->dev.parent;
119 	struct da8xx_rproc *drproc = (struct da8xx_rproc *)rproc->priv;
120 	struct clk *dsp_clk = drproc->dsp_clk;
121 
122 	/* hw requires the start (boot) address be on 1KB boundary */
123 	if (rproc->bootaddr & 0x3ff) {
124 		dev_err(dev, "invalid boot address: must be aligned to 1KB\n");
125 
126 		return -EINVAL;
127 	}
128 
129 	writel(rproc->bootaddr, drproc->bootreg);
130 
131 	clk_enable(dsp_clk);
132 	davinci_clk_reset_deassert(dsp_clk);
133 
134 	return 0;
135 }
136 
137 static int da8xx_rproc_stop(struct rproc *rproc)
138 {
139 	struct da8xx_rproc *drproc = rproc->priv;
140 
141 	clk_disable(drproc->dsp_clk);
142 
143 	return 0;
144 }
145 
146 /* kick a virtqueue */
147 static void da8xx_rproc_kick(struct rproc *rproc, int vqid)
148 {
149 	struct da8xx_rproc *drproc = (struct da8xx_rproc *)rproc->priv;
150 
151 	/* Interupt remote proc */
152 	writel(SYSCFG_CHIPSIG2, drproc->chipsig);
153 }
154 
155 static struct rproc_ops da8xx_rproc_ops = {
156 	.start = da8xx_rproc_start,
157 	.stop = da8xx_rproc_stop,
158 	.kick = da8xx_rproc_kick,
159 };
160 
161 static int reset_assert(struct device *dev)
162 {
163 	struct clk *dsp_clk;
164 
165 	dsp_clk = clk_get(dev, NULL);
166 	if (IS_ERR(dsp_clk)) {
167 		dev_err(dev, "clk_get error: %ld\n", PTR_ERR(dsp_clk));
168 		return PTR_ERR(dsp_clk);
169 	}
170 
171 	davinci_clk_reset_assert(dsp_clk);
172 	clk_put(dsp_clk);
173 
174 	return 0;
175 }
176 
177 static int da8xx_rproc_probe(struct platform_device *pdev)
178 {
179 	struct device *dev = &pdev->dev;
180 	struct da8xx_rproc *drproc;
181 	struct rproc *rproc;
182 	struct irq_data *irq_data;
183 	struct resource *bootreg_res;
184 	struct resource *chipsig_res;
185 	struct clk *dsp_clk;
186 	void __iomem *chipsig;
187 	void __iomem *bootreg;
188 	int irq;
189 	int ret;
190 
191 	irq = platform_get_irq(pdev, 0);
192 	if (irq < 0) {
193 		dev_err(dev, "platform_get_irq(pdev, 0) error: %d\n", irq);
194 		return irq;
195 	}
196 
197 	irq_data = irq_get_irq_data(irq);
198 	if (!irq_data) {
199 		dev_err(dev, "irq_get_irq_data(%d): NULL\n", irq);
200 		return -EINVAL;
201 	}
202 
203 	bootreg_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
204 	bootreg = devm_ioremap_resource(dev, bootreg_res);
205 	if (IS_ERR(bootreg))
206 		return PTR_ERR(bootreg);
207 
208 	chipsig_res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
209 	chipsig = devm_ioremap_resource(dev, chipsig_res);
210 	if (IS_ERR(chipsig))
211 		return PTR_ERR(chipsig);
212 
213 	dsp_clk = devm_clk_get(dev, NULL);
214 	if (IS_ERR(dsp_clk)) {
215 		dev_err(dev, "clk_get error: %ld\n", PTR_ERR(dsp_clk));
216 
217 		return PTR_ERR(dsp_clk);
218 	}
219 
220 	rproc = rproc_alloc(dev, "dsp", &da8xx_rproc_ops, da8xx_fw_name,
221 		sizeof(*drproc));
222 	if (!rproc)
223 		return -ENOMEM;
224 
225 	drproc = rproc->priv;
226 	drproc->rproc = rproc;
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_put(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_put(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 		.owner = THIS_MODULE,
304 	},
305 };
306 
307 module_platform_driver(da8xx_rproc_driver);
308 
309 MODULE_LICENSE("GPL v2");
310 MODULE_DESCRIPTION("DA8XX Remote Processor control driver");
311