Root/drivers/gpio/gpio-stp-xway.c

1/*
2 * This program is free software; you can redistribute it and/or modify it
3 * under the terms of the GNU General Public License version 2 as published
4 * by the Free Software Foundation.
5 *
6 * Copyright (C) 2012 John Crispin <blogic@openwrt.org>
7 *
8 */
9
10#include <linux/slab.h>
11#include <linux/init.h>
12#include <linux/module.h>
13#include <linux/types.h>
14#include <linux/of_platform.h>
15#include <linux/mutex.h>
16#include <linux/gpio.h>
17#include <linux/io.h>
18#include <linux/of_gpio.h>
19#include <linux/clk.h>
20#include <linux/err.h>
21
22#include <lantiq_soc.h>
23
24/*
25 * The Serial To Parallel (STP) is found on MIPS based Lantiq socs. It is a
26 * peripheral controller used to drive external shift register cascades. At most
27 * 3 groups of 8 bits can be driven. The hardware is able to allow the DSL modem
28 * to drive the 2 LSBs of the cascade automatically.
29 */
30
31/* control register 0 */
32#define XWAY_STP_CON0 0x00
33/* control register 1 */
34#define XWAY_STP_CON1 0x04
35/* data register 0 */
36#define XWAY_STP_CPU0 0x08
37/* data register 1 */
38#define XWAY_STP_CPU1 0x0C
39/* access register */
40#define XWAY_STP_AR 0x10
41
42/* software or hardware update select bit */
43#define XWAY_STP_CON_SWU BIT(31)
44
45/* automatic update rates */
46#define XWAY_STP_2HZ 0
47#define XWAY_STP_4HZ BIT(23)
48#define XWAY_STP_8HZ BIT(24)
49#define XWAY_STP_10HZ (BIT(24) | BIT(23))
50#define XWAY_STP_SPEED_MASK (0xf << 23)
51
52/* clock source for automatic update */
53#define XWAY_STP_UPD_FPI BIT(31)
54#define XWAY_STP_UPD_MASK (BIT(31) | BIT(30))
55
56/* let the adsl core drive the 2 LSBs */
57#define XWAY_STP_ADSL_SHIFT 24
58#define XWAY_STP_ADSL_MASK 0x3
59
60/* 2 groups of 3 bits can be driven by the phys */
61#define XWAY_STP_PHY_MASK 0x3
62#define XWAY_STP_PHY1_SHIFT 27
63#define XWAY_STP_PHY2_SHIFT 15
64
65/* STP has 3 groups of 8 bits */
66#define XWAY_STP_GROUP0 BIT(0)
67#define XWAY_STP_GROUP1 BIT(1)
68#define XWAY_STP_GROUP2 BIT(2)
69#define XWAY_STP_GROUP_MASK (0x7)
70
71/* Edge configuration bits */
72#define XWAY_STP_FALLING BIT(26)
73#define XWAY_STP_EDGE_MASK BIT(26)
74
75#define xway_stp_r32(m, reg) __raw_readl(m + reg)
76#define xway_stp_w32(m, val, reg) __raw_writel(val, m + reg)
77#define xway_stp_w32_mask(m, clear, set, reg) \
78        ltq_w32((ltq_r32(m + reg) & ~(clear)) | (set), \
79        m + reg)
80
81struct xway_stp {
82    struct gpio_chip gc;
83    void __iomem *virt;
84    u32 edge; /* rising or falling edge triggered shift register */
85    u16 shadow; /* shadow the shift registers state */
86    u8 groups; /* we can drive 1-3 groups of 8bit each */
87    u8 dsl; /* the 2 LSBs can be driven by the dsl core */
88    u8 phy1; /* 3 bits can be driven by phy1 */
89    u8 phy2; /* 3 bits can be driven by phy2 */
90    u8 reserved; /* mask out the hw driven bits in gpio_request */
91};
92
93/**
94 * xway_stp_set() - gpio_chip->set - set gpios.
95 * @gc: Pointer to gpio_chip device structure.
96 * @gpio: GPIO signal number.
97 * @val: Value to be written to specified signal.
98 *
99 * Set the shadow value and call ltq_ebu_apply.
100 */
101static void xway_stp_set(struct gpio_chip *gc, unsigned gpio, int val)
102{
103    struct xway_stp *chip =
104        container_of(gc, struct xway_stp, gc);
105
106    if (val)
107        chip->shadow |= BIT(gpio);
108    else
109        chip->shadow &= ~BIT(gpio);
110    xway_stp_w32(chip->virt, chip->shadow, XWAY_STP_CPU0);
111    xway_stp_w32_mask(chip->virt, 0, XWAY_STP_CON_SWU, XWAY_STP_CON0);
112}
113
114/**
115 * xway_stp_dir_out() - gpio_chip->dir_out - set gpio direction.
116 * @gc: Pointer to gpio_chip device structure.
117 * @gpio: GPIO signal number.
118 * @val: Value to be written to specified signal.
119 *
120 * Same as xway_stp_set, always returns 0.
121 */
122static int xway_stp_dir_out(struct gpio_chip *gc, unsigned gpio, int val)
123{
124    xway_stp_set(gc, gpio, val);
125
126    return 0;
127}
128
129/**
130 * xway_stp_request() - gpio_chip->request
131 * @gc: Pointer to gpio_chip device structure.
132 * @gpio: GPIO signal number.
133 *
134 * We mask out the HW driven pins
135 */
136static int xway_stp_request(struct gpio_chip *gc, unsigned gpio)
137{
138    struct xway_stp *chip =
139        container_of(gc, struct xway_stp, gc);
140
141    if ((gpio < 8) && (chip->reserved & BIT(gpio))) {
142        dev_err(gc->dev, "GPIO %d is driven by hardware\n", gpio);
143        return -ENODEV;
144    }
145
146    return 0;
147}
148
149/**
150 * xway_stp_hw_init() - Configure the STP unit and enable the clock gate
151 * @virt: pointer to the remapped register range
152 */
153static int xway_stp_hw_init(struct xway_stp *chip)
154{
155    /* sane defaults */
156    xway_stp_w32(chip->virt, 0, XWAY_STP_AR);
157    xway_stp_w32(chip->virt, 0, XWAY_STP_CPU0);
158    xway_stp_w32(chip->virt, 0, XWAY_STP_CPU1);
159    xway_stp_w32(chip->virt, XWAY_STP_CON_SWU, XWAY_STP_CON0);
160    xway_stp_w32(chip->virt, 0, XWAY_STP_CON1);
161
162    /* apply edge trigger settings for the shift register */
163    xway_stp_w32_mask(chip->virt, XWAY_STP_EDGE_MASK,
164                chip->edge, XWAY_STP_CON0);
165
166    /* apply led group settings */
167    xway_stp_w32_mask(chip->virt, XWAY_STP_GROUP_MASK,
168                chip->groups, XWAY_STP_CON1);
169
170    /* tell the hardware which pins are controlled by the dsl modem */
171    xway_stp_w32_mask(chip->virt,
172            XWAY_STP_ADSL_MASK << XWAY_STP_ADSL_SHIFT,
173            chip->dsl << XWAY_STP_ADSL_SHIFT,
174            XWAY_STP_CON0);
175
176    /* tell the hardware which pins are controlled by the phys */
177    xway_stp_w32_mask(chip->virt,
178            XWAY_STP_PHY_MASK << XWAY_STP_PHY1_SHIFT,
179            chip->phy1 << XWAY_STP_PHY1_SHIFT,
180            XWAY_STP_CON0);
181    xway_stp_w32_mask(chip->virt,
182            XWAY_STP_PHY_MASK << XWAY_STP_PHY2_SHIFT,
183            chip->phy2 << XWAY_STP_PHY2_SHIFT,
184            XWAY_STP_CON1);
185
186    /* mask out the hw driven bits in gpio_request */
187    chip->reserved = (chip->phy2 << 5) | (chip->phy1 << 2) | chip->dsl;
188
189    /*
190     * if we have pins that are driven by hw, we need to tell the stp what
191     * clock to use as a timer.
192     */
193    if (chip->reserved)
194        xway_stp_w32_mask(chip->virt, XWAY_STP_UPD_MASK,
195            XWAY_STP_UPD_FPI, XWAY_STP_CON1);
196
197    return 0;
198}
199
200static int __devinit xway_stp_probe(struct platform_device *pdev)
201{
202    struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
203    const __be32 *shadow, *groups, *dsl, *phy;
204    struct xway_stp *chip;
205    struct clk *clk;
206    int ret = 0;
207
208    if (!res) {
209        dev_err(&pdev->dev, "failed to request STP resource\n");
210        return -ENOENT;
211    }
212
213    chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
214    if (!chip)
215        return -ENOMEM;
216
217    chip->virt = devm_request_and_ioremap(&pdev->dev, res);
218    if (!chip->virt) {
219        dev_err(&pdev->dev, "failed to remap STP memory\n");
220        return -ENOMEM;
221    }
222    chip->gc.dev = &pdev->dev;
223    chip->gc.label = "stp-xway";
224    chip->gc.direction_output = xway_stp_dir_out;
225    chip->gc.set = xway_stp_set;
226    chip->gc.request = xway_stp_request;
227    chip->gc.base = -1;
228    chip->gc.owner = THIS_MODULE;
229
230    /* store the shadow value if one was passed by the devicetree */
231    shadow = of_get_property(pdev->dev.of_node, "lantiq,shadow", NULL);
232    if (shadow)
233        chip->shadow = be32_to_cpu(*shadow);
234
235    /* find out which gpio groups should be enabled */
236    groups = of_get_property(pdev->dev.of_node, "lantiq,groups", NULL);
237    if (groups)
238        chip->groups = be32_to_cpu(*groups) & XWAY_STP_GROUP_MASK;
239    else
240        chip->groups = XWAY_STP_GROUP0;
241    chip->gc.ngpio = fls(chip->groups) * 8;
242
243    /* find out which gpios are controlled by the dsl core */
244    dsl = of_get_property(pdev->dev.of_node, "lantiq,dsl", NULL);
245    if (dsl)
246        chip->dsl = be32_to_cpu(*dsl) & XWAY_STP_ADSL_MASK;
247
248    /* find out which gpios are controlled by the phys */
249    if (of_machine_is_compatible("lantiq,ar9") ||
250            of_machine_is_compatible("lantiq,gr9") ||
251            of_machine_is_compatible("lantiq,vr9")) {
252        phy = of_get_property(pdev->dev.of_node, "lantiq,phy1", NULL);
253        if (phy)
254            chip->phy1 = be32_to_cpu(*phy) & XWAY_STP_PHY_MASK;
255        phy = of_get_property(pdev->dev.of_node, "lantiq,phy2", NULL);
256        if (phy)
257            chip->phy2 = be32_to_cpu(*phy) & XWAY_STP_PHY_MASK;
258    }
259
260    /* check which edge trigger we should use, default to a falling edge */
261    if (!of_find_property(pdev->dev.of_node, "lantiq,rising", NULL))
262        chip->edge = XWAY_STP_FALLING;
263
264    clk = clk_get(&pdev->dev, NULL);
265    if (IS_ERR(clk)) {
266        dev_err(&pdev->dev, "Failed to get clock\n");
267        return PTR_ERR(clk);
268    }
269    clk_enable(clk);
270
271    ret = xway_stp_hw_init(chip);
272    if (!ret)
273        ret = gpiochip_add(&chip->gc);
274
275    if (!ret)
276        dev_info(&pdev->dev, "Init done\n");
277
278    return ret;
279}
280
281static const struct of_device_id xway_stp_match[] = {
282    { .compatible = "lantiq,gpio-stp-xway" },
283    {},
284};
285MODULE_DEVICE_TABLE(of, xway_stp_match);
286
287static struct platform_driver xway_stp_driver = {
288    .probe = xway_stp_probe,
289    .driver = {
290        .name = "gpio-stp-xway",
291        .owner = THIS_MODULE,
292        .of_match_table = xway_stp_match,
293    },
294};
295
296int __init xway_stp_init(void)
297{
298    return platform_driver_register(&xway_stp_driver);
299}
300
301subsys_initcall(xway_stp_init);
302

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