1 /*
2  * Atmel AT91 SAM9 SoCs reset code
3  *
4  * Copyright (C) 2007 Atmel Corporation.
5  * Copyright (C) 2011 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
6  * Copyright (C) 2014 Free Electrons
7  *
8  * This file is licensed under the terms of the GNU General Public
9  * License version 2.  This program is licensed "as is" without any
10  * warranty of any kind, whether express or implied.
11  */
12 
13 #include <linux/clk.h>
14 #include <linux/io.h>
15 #include <linux/module.h>
16 #include <linux/of.h>
17 #include <linux/of_address.h>
18 #include <linux/platform_device.h>
19 #include <linux/printk.h>
20 
21 #include <soc/at91/at91sam9_ddrsdr.h>
22 
23 #define AT91_SHDW_CR	0x00		/* Shut Down Control Register */
24 #define AT91_SHDW_SHDW		BIT(0)			/* Shut Down command */
25 #define AT91_SHDW_KEY		(0xa5 << 24)		/* KEY Password */
26 
27 #define AT91_SHDW_MR	0x04		/* Shut Down Mode Register */
28 #define AT91_SHDW_WKMODE0	GENMASK(2, 0)		/* Wake-up 0 Mode Selection */
29 #define AT91_SHDW_CPTWK0_MAX	0xf			/* Maximum Counter On Wake Up 0 */
30 #define AT91_SHDW_CPTWK0	(AT91_SHDW_CPTWK0_MAX << 4) /* Counter On Wake Up 0 */
31 #define AT91_SHDW_CPTWK0_(x)	((x) << 4)
32 #define AT91_SHDW_RTTWKEN	BIT(16)			/* Real Time Timer Wake-up Enable */
33 #define AT91_SHDW_RTCWKEN	BIT(17)			/* Real Time Clock Wake-up Enable */
34 
35 #define AT91_SHDW_SR	0x08		/* Shut Down Status Register */
36 #define AT91_SHDW_WAKEUP0	BIT(0)			/* Wake-up 0 Status */
37 #define AT91_SHDW_RTTWK		BIT(16)			/* Real-time Timer Wake-up */
38 #define AT91_SHDW_RTCWK		BIT(17)			/* Real-time Clock Wake-up [SAM9RL] */
39 
40 enum wakeup_type {
41 	AT91_SHDW_WKMODE0_NONE		= 0,
42 	AT91_SHDW_WKMODE0_HIGH		= 1,
43 	AT91_SHDW_WKMODE0_LOW		= 2,
44 	AT91_SHDW_WKMODE0_ANYLEVEL	= 3,
45 };
46 
47 static const char *shdwc_wakeup_modes[] = {
48 	[AT91_SHDW_WKMODE0_NONE]	= "none",
49 	[AT91_SHDW_WKMODE0_HIGH]	= "high",
50 	[AT91_SHDW_WKMODE0_LOW]		= "low",
51 	[AT91_SHDW_WKMODE0_ANYLEVEL]	= "any",
52 };
53 
54 static struct shdwc {
55 	struct clk *sclk;
56 	void __iomem *shdwc_base;
57 	void __iomem *mpddrc_base;
58 } at91_shdwc;
59 
60 static void __init at91_wakeup_status(struct platform_device *pdev)
61 {
62 	const char *reason;
63 	u32 reg = readl(at91_shdwc.shdwc_base + AT91_SHDW_SR);
64 
65 	/* Simple power-on, just bail out */
66 	if (!reg)
67 		return;
68 
69 	if (reg & AT91_SHDW_RTTWK)
70 		reason = "RTT";
71 	else if (reg & AT91_SHDW_RTCWK)
72 		reason = "RTC";
73 	else
74 		reason = "unknown";
75 
76 	dev_info(&pdev->dev, "Wake-Up source: %s\n", reason);
77 }
78 
79 static void at91_poweroff(void)
80 {
81 	asm volatile(
82 		/* Align to cache lines */
83 		".balign 32\n\t"
84 
85 		/* Ensure AT91_SHDW_CR is in the TLB by reading it */
86 		"	ldr	r6, [%2, #" __stringify(AT91_SHDW_CR) "]\n\t"
87 
88 		/* Power down SDRAM0 */
89 		"	tst	%0, #0\n\t"
90 		"	beq	1f\n\t"
91 		"	str	%1, [%0, #" __stringify(AT91_DDRSDRC_LPR) "]\n\t"
92 		/* Shutdown CPU */
93 		"1:	str	%3, [%2, #" __stringify(AT91_SHDW_CR) "]\n\t"
94 
95 		"	b	.\n\t"
96 		:
97 		: "r" (at91_shdwc.mpddrc_base),
98 		  "r" cpu_to_le32(AT91_DDRSDRC_LPDDR2_PWOFF),
99 		  "r" (at91_shdwc.shdwc_base),
100 		  "r" cpu_to_le32(AT91_SHDW_KEY | AT91_SHDW_SHDW)
101 		: "r6");
102 }
103 
104 static int at91_poweroff_get_wakeup_mode(struct device_node *np)
105 {
106 	const char *pm;
107 	unsigned int i;
108 	int err;
109 
110 	err = of_property_read_string(np, "atmel,wakeup-mode", &pm);
111 	if (err < 0)
112 		return AT91_SHDW_WKMODE0_ANYLEVEL;
113 
114 	for (i = 0; i < ARRAY_SIZE(shdwc_wakeup_modes); i++)
115 		if (!strcasecmp(pm, shdwc_wakeup_modes[i]))
116 			return i;
117 
118 	return -ENODEV;
119 }
120 
121 static void at91_poweroff_dt_set_wakeup_mode(struct platform_device *pdev)
122 {
123 	struct device_node *np = pdev->dev.of_node;
124 	int wakeup_mode;
125 	u32 mode = 0, tmp;
126 
127 	wakeup_mode = at91_poweroff_get_wakeup_mode(np);
128 	if (wakeup_mode < 0) {
129 		dev_warn(&pdev->dev, "shdwc unknown wakeup mode\n");
130 		return;
131 	}
132 
133 	if (!of_property_read_u32(np, "atmel,wakeup-counter", &tmp)) {
134 		if (tmp > AT91_SHDW_CPTWK0_MAX) {
135 			dev_warn(&pdev->dev,
136 				 "shdwc wakeup counter 0x%x > 0x%x reduce it to 0x%x\n",
137 				 tmp, AT91_SHDW_CPTWK0_MAX, AT91_SHDW_CPTWK0_MAX);
138 			tmp = AT91_SHDW_CPTWK0_MAX;
139 		}
140 		mode |= AT91_SHDW_CPTWK0_(tmp);
141 	}
142 
143 	if (of_property_read_bool(np, "atmel,wakeup-rtc-timer"))
144 			mode |= AT91_SHDW_RTCWKEN;
145 
146 	if (of_property_read_bool(np, "atmel,wakeup-rtt-timer"))
147 			mode |= AT91_SHDW_RTTWKEN;
148 
149 	writel(wakeup_mode | mode, at91_shdwc.shdwc_base + AT91_SHDW_MR);
150 }
151 
152 static int __init at91_poweroff_probe(struct platform_device *pdev)
153 {
154 	struct device_node *np;
155 	u32 ddr_type;
156 	int ret;
157 
158 	at91_shdwc.shdwc_base = devm_platform_ioremap_resource(pdev, 0);
159 	if (IS_ERR(at91_shdwc.shdwc_base))
160 		return PTR_ERR(at91_shdwc.shdwc_base);
161 
162 	at91_shdwc.sclk = devm_clk_get(&pdev->dev, NULL);
163 	if (IS_ERR(at91_shdwc.sclk))
164 		return PTR_ERR(at91_shdwc.sclk);
165 
166 	ret = clk_prepare_enable(at91_shdwc.sclk);
167 	if (ret) {
168 		dev_err(&pdev->dev, "Could not enable slow clock\n");
169 		return ret;
170 	}
171 
172 	at91_wakeup_status(pdev);
173 
174 	if (pdev->dev.of_node)
175 		at91_poweroff_dt_set_wakeup_mode(pdev);
176 
177 	np = of_find_compatible_node(NULL, NULL, "atmel,sama5d3-ddramc");
178 	if (np) {
179 		at91_shdwc.mpddrc_base = of_iomap(np, 0);
180 		of_node_put(np);
181 
182 		if (!at91_shdwc.mpddrc_base) {
183 			ret = -ENOMEM;
184 			goto clk_disable;
185 		}
186 
187 		ddr_type = readl(at91_shdwc.mpddrc_base + AT91_DDRSDRC_MDR) &
188 				 AT91_DDRSDRC_MD;
189 		if (ddr_type != AT91_DDRSDRC_MD_LPDDR2 &&
190 		    ddr_type != AT91_DDRSDRC_MD_LPDDR3) {
191 			iounmap(at91_shdwc.mpddrc_base);
192 			at91_shdwc.mpddrc_base = NULL;
193 		}
194 	}
195 
196 	pm_power_off = at91_poweroff;
197 
198 	return 0;
199 
200 clk_disable:
201 	clk_disable_unprepare(at91_shdwc.sclk);
202 	return ret;
203 }
204 
205 static int __exit at91_poweroff_remove(struct platform_device *pdev)
206 {
207 	if (pm_power_off == at91_poweroff)
208 		pm_power_off = NULL;
209 
210 	if (at91_shdwc.mpddrc_base)
211 		iounmap(at91_shdwc.mpddrc_base);
212 
213 	clk_disable_unprepare(at91_shdwc.sclk);
214 
215 	return 0;
216 }
217 
218 static const struct of_device_id at91_poweroff_of_match[] = {
219 	{ .compatible = "atmel,at91sam9260-shdwc", },
220 	{ .compatible = "atmel,at91sam9rl-shdwc", },
221 	{ .compatible = "atmel,at91sam9x5-shdwc", },
222 	{ /*sentinel*/ }
223 };
224 MODULE_DEVICE_TABLE(of, at91_poweroff_of_match);
225 
226 static struct platform_driver at91_poweroff_driver = {
227 	.remove = __exit_p(at91_poweroff_remove),
228 	.driver = {
229 		.name = "at91-poweroff",
230 		.of_match_table = at91_poweroff_of_match,
231 	},
232 };
233 module_platform_driver_probe(at91_poweroff_driver, at91_poweroff_probe);
234 
235 MODULE_AUTHOR("Atmel Corporation");
236 MODULE_DESCRIPTION("Shutdown driver for Atmel SoCs");
237 MODULE_LICENSE("GPL v2");
238