1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright 2019 American Megatrends International LLC.
4  *
5  * Author: Karthikeyan Mani <karthikeyanm@amiindia.co.in>
6  */
7 
8 #include <linux/bitfield.h>
9 #include <linux/clk.h>
10 #include <linux/gpio/driver.h>
11 #include <linux/hashtable.h>
12 #include <linux/init.h>
13 #include <linux/io.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/platform_device.h>
17 #include <linux/seq_file.h>
18 #include <linux/spinlock.h>
19 #include <linux/string.h>
20 
21 #define ASPEED_SGPIO_CTRL		0x54
22 
23 #define ASPEED_SGPIO_CLK_DIV_MASK	GENMASK(31, 16)
24 #define ASPEED_SGPIO_ENABLE		BIT(0)
25 #define ASPEED_SGPIO_PINS_SHIFT		6
26 
27 struct aspeed_sgpio_pdata {
28 	const u32 pin_mask;
29 };
30 
31 struct aspeed_sgpio {
32 	struct gpio_chip chip;
33 	struct device *dev;
34 	struct clk *pclk;
35 	raw_spinlock_t lock;
36 	void __iomem *base;
37 	int irq;
38 };
39 
40 struct aspeed_sgpio_bank {
41 	u16    val_regs;
42 	u16    rdata_reg;
43 	u16    irq_regs;
44 	u16    tolerance_regs;
45 	const char  names[4][3];
46 };
47 
48 /*
49  * Note: The "value" register returns the input value when the GPIO is
50  *	 configured as an input.
51  *
52  *	 The "rdata" register returns the output value when the GPIO is
53  *	 configured as an output.
54  */
55 static const struct aspeed_sgpio_bank aspeed_sgpio_banks[] = {
56 	{
57 		.val_regs = 0x0000,
58 		.rdata_reg = 0x0070,
59 		.irq_regs = 0x0004,
60 		.tolerance_regs = 0x0018,
61 		.names = { "A", "B", "C", "D" },
62 	},
63 	{
64 		.val_regs = 0x001C,
65 		.rdata_reg = 0x0074,
66 		.irq_regs = 0x0020,
67 		.tolerance_regs = 0x0034,
68 		.names = { "E", "F", "G", "H" },
69 	},
70 	{
71 		.val_regs = 0x0038,
72 		.rdata_reg = 0x0078,
73 		.irq_regs = 0x003C,
74 		.tolerance_regs = 0x0050,
75 		.names = { "I", "J", "K", "L" },
76 	},
77 	{
78 		.val_regs = 0x0090,
79 		.rdata_reg = 0x007C,
80 		.irq_regs = 0x0094,
81 		.tolerance_regs = 0x00A8,
82 		.names = { "M", "N", "O", "P" },
83 	},
84 };
85 
86 enum aspeed_sgpio_reg {
87 	reg_val,
88 	reg_rdata,
89 	reg_irq_enable,
90 	reg_irq_type0,
91 	reg_irq_type1,
92 	reg_irq_type2,
93 	reg_irq_status,
94 	reg_tolerance,
95 };
96 
97 #define GPIO_VAL_VALUE      0x00
98 #define GPIO_IRQ_ENABLE     0x00
99 #define GPIO_IRQ_TYPE0      0x04
100 #define GPIO_IRQ_TYPE1      0x08
101 #define GPIO_IRQ_TYPE2      0x0C
102 #define GPIO_IRQ_STATUS     0x10
103 
bank_reg(struct aspeed_sgpio * gpio,const struct aspeed_sgpio_bank * bank,const enum aspeed_sgpio_reg reg)104 static void __iomem *bank_reg(struct aspeed_sgpio *gpio,
105 				     const struct aspeed_sgpio_bank *bank,
106 				     const enum aspeed_sgpio_reg reg)
107 {
108 	switch (reg) {
109 	case reg_val:
110 		return gpio->base + bank->val_regs + GPIO_VAL_VALUE;
111 	case reg_rdata:
112 		return gpio->base + bank->rdata_reg;
113 	case reg_irq_enable:
114 		return gpio->base + bank->irq_regs + GPIO_IRQ_ENABLE;
115 	case reg_irq_type0:
116 		return gpio->base + bank->irq_regs + GPIO_IRQ_TYPE0;
117 	case reg_irq_type1:
118 		return gpio->base + bank->irq_regs + GPIO_IRQ_TYPE1;
119 	case reg_irq_type2:
120 		return gpio->base + bank->irq_regs + GPIO_IRQ_TYPE2;
121 	case reg_irq_status:
122 		return gpio->base + bank->irq_regs + GPIO_IRQ_STATUS;
123 	case reg_tolerance:
124 		return gpio->base + bank->tolerance_regs;
125 	default:
126 		/* acturally if code runs to here, it's an error case */
127 		BUG();
128 	}
129 }
130 
131 #define GPIO_BANK(x)    ((x) >> 6)
132 #define GPIO_OFFSET(x)  ((x) & GENMASK(5, 0))
133 #define GPIO_BIT(x)     BIT(GPIO_OFFSET(x) >> 1)
134 
to_bank(unsigned int offset)135 static const struct aspeed_sgpio_bank *to_bank(unsigned int offset)
136 {
137 	unsigned int bank;
138 
139 	bank = GPIO_BANK(offset);
140 
141 	WARN_ON(bank >= ARRAY_SIZE(aspeed_sgpio_banks));
142 	return &aspeed_sgpio_banks[bank];
143 }
144 
aspeed_sgpio_init_valid_mask(struct gpio_chip * gc,unsigned long * valid_mask,unsigned int ngpios)145 static int aspeed_sgpio_init_valid_mask(struct gpio_chip *gc,
146 		unsigned long *valid_mask, unsigned int ngpios)
147 {
148 	bitmap_set(valid_mask, 0, ngpios);
149 	return 0;
150 }
151 
aspeed_sgpio_irq_init_valid_mask(struct gpio_chip * gc,unsigned long * valid_mask,unsigned int ngpios)152 static void aspeed_sgpio_irq_init_valid_mask(struct gpio_chip *gc,
153 		unsigned long *valid_mask, unsigned int ngpios)
154 {
155 	unsigned int i;
156 
157 	/* input GPIOs are even bits */
158 	for (i = 0; i < ngpios; i++) {
159 		if (i % 2)
160 			clear_bit(i, valid_mask);
161 	}
162 }
163 
aspeed_sgpio_is_input(unsigned int offset)164 static bool aspeed_sgpio_is_input(unsigned int offset)
165 {
166 	return !(offset % 2);
167 }
168 
aspeed_sgpio_get(struct gpio_chip * gc,unsigned int offset)169 static int aspeed_sgpio_get(struct gpio_chip *gc, unsigned int offset)
170 {
171 	struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
172 	const struct aspeed_sgpio_bank *bank = to_bank(offset);
173 	unsigned long flags;
174 	enum aspeed_sgpio_reg reg;
175 	int rc = 0;
176 
177 	raw_spin_lock_irqsave(&gpio->lock, flags);
178 
179 	reg = aspeed_sgpio_is_input(offset) ? reg_val : reg_rdata;
180 	rc = !!(ioread32(bank_reg(gpio, bank, reg)) & GPIO_BIT(offset));
181 
182 	raw_spin_unlock_irqrestore(&gpio->lock, flags);
183 
184 	return rc;
185 }
186 
sgpio_set_value(struct gpio_chip * gc,unsigned int offset,int val)187 static int sgpio_set_value(struct gpio_chip *gc, unsigned int offset, int val)
188 {
189 	struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
190 	const struct aspeed_sgpio_bank *bank = to_bank(offset);
191 	void __iomem *addr_r, *addr_w;
192 	u32 reg = 0;
193 
194 	if (aspeed_sgpio_is_input(offset))
195 		return -EINVAL;
196 
197 	/* Since this is an output, read the cached value from rdata, then
198 	 * update val. */
199 	addr_r = bank_reg(gpio, bank, reg_rdata);
200 	addr_w = bank_reg(gpio, bank, reg_val);
201 
202 	reg = ioread32(addr_r);
203 
204 	if (val)
205 		reg |= GPIO_BIT(offset);
206 	else
207 		reg &= ~GPIO_BIT(offset);
208 
209 	iowrite32(reg, addr_w);
210 
211 	return 0;
212 }
213 
aspeed_sgpio_set(struct gpio_chip * gc,unsigned int offset,int val)214 static void aspeed_sgpio_set(struct gpio_chip *gc, unsigned int offset, int val)
215 {
216 	struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
217 	unsigned long flags;
218 
219 	raw_spin_lock_irqsave(&gpio->lock, flags);
220 
221 	sgpio_set_value(gc, offset, val);
222 
223 	raw_spin_unlock_irqrestore(&gpio->lock, flags);
224 }
225 
aspeed_sgpio_dir_in(struct gpio_chip * gc,unsigned int offset)226 static int aspeed_sgpio_dir_in(struct gpio_chip *gc, unsigned int offset)
227 {
228 	return aspeed_sgpio_is_input(offset) ? 0 : -EINVAL;
229 }
230 
aspeed_sgpio_dir_out(struct gpio_chip * gc,unsigned int offset,int val)231 static int aspeed_sgpio_dir_out(struct gpio_chip *gc, unsigned int offset, int val)
232 {
233 	struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
234 	unsigned long flags;
235 	int rc;
236 
237 	/* No special action is required for setting the direction; we'll
238 	 * error-out in sgpio_set_value if this isn't an output GPIO */
239 
240 	raw_spin_lock_irqsave(&gpio->lock, flags);
241 	rc = sgpio_set_value(gc, offset, val);
242 	raw_spin_unlock_irqrestore(&gpio->lock, flags);
243 
244 	return rc;
245 }
246 
aspeed_sgpio_get_direction(struct gpio_chip * gc,unsigned int offset)247 static int aspeed_sgpio_get_direction(struct gpio_chip *gc, unsigned int offset)
248 {
249 	return !!aspeed_sgpio_is_input(offset);
250 }
251 
irqd_to_aspeed_sgpio_data(struct irq_data * d,struct aspeed_sgpio ** gpio,const struct aspeed_sgpio_bank ** bank,u32 * bit,int * offset)252 static void irqd_to_aspeed_sgpio_data(struct irq_data *d,
253 					struct aspeed_sgpio **gpio,
254 					const struct aspeed_sgpio_bank **bank,
255 					u32 *bit, int *offset)
256 {
257 	struct aspeed_sgpio *internal;
258 
259 	*offset = irqd_to_hwirq(d);
260 	internal = irq_data_get_irq_chip_data(d);
261 	WARN_ON(!internal);
262 
263 	*gpio = internal;
264 	*bank = to_bank(*offset);
265 	*bit = GPIO_BIT(*offset);
266 }
267 
aspeed_sgpio_irq_ack(struct irq_data * d)268 static void aspeed_sgpio_irq_ack(struct irq_data *d)
269 {
270 	const struct aspeed_sgpio_bank *bank;
271 	struct aspeed_sgpio *gpio;
272 	unsigned long flags;
273 	void __iomem *status_addr;
274 	int offset;
275 	u32 bit;
276 
277 	irqd_to_aspeed_sgpio_data(d, &gpio, &bank, &bit, &offset);
278 
279 	status_addr = bank_reg(gpio, bank, reg_irq_status);
280 
281 	raw_spin_lock_irqsave(&gpio->lock, flags);
282 
283 	iowrite32(bit, status_addr);
284 
285 	raw_spin_unlock_irqrestore(&gpio->lock, flags);
286 }
287 
aspeed_sgpio_irq_set_mask(struct irq_data * d,bool set)288 static void aspeed_sgpio_irq_set_mask(struct irq_data *d, bool set)
289 {
290 	const struct aspeed_sgpio_bank *bank;
291 	struct aspeed_sgpio *gpio;
292 	unsigned long flags;
293 	u32 reg, bit;
294 	void __iomem *addr;
295 	int offset;
296 
297 	irqd_to_aspeed_sgpio_data(d, &gpio, &bank, &bit, &offset);
298 	addr = bank_reg(gpio, bank, reg_irq_enable);
299 
300 	/* Unmasking the IRQ */
301 	if (set)
302 		gpiochip_enable_irq(&gpio->chip, irqd_to_hwirq(d));
303 
304 	raw_spin_lock_irqsave(&gpio->lock, flags);
305 
306 	reg = ioread32(addr);
307 	if (set)
308 		reg |= bit;
309 	else
310 		reg &= ~bit;
311 
312 	iowrite32(reg, addr);
313 
314 	raw_spin_unlock_irqrestore(&gpio->lock, flags);
315 
316 	/* Masking the IRQ */
317 	if (!set)
318 		gpiochip_disable_irq(&gpio->chip, irqd_to_hwirq(d));
319 
320 
321 }
322 
aspeed_sgpio_irq_mask(struct irq_data * d)323 static void aspeed_sgpio_irq_mask(struct irq_data *d)
324 {
325 	aspeed_sgpio_irq_set_mask(d, false);
326 }
327 
aspeed_sgpio_irq_unmask(struct irq_data * d)328 static void aspeed_sgpio_irq_unmask(struct irq_data *d)
329 {
330 	aspeed_sgpio_irq_set_mask(d, true);
331 }
332 
aspeed_sgpio_set_type(struct irq_data * d,unsigned int type)333 static int aspeed_sgpio_set_type(struct irq_data *d, unsigned int type)
334 {
335 	u32 type0 = 0;
336 	u32 type1 = 0;
337 	u32 type2 = 0;
338 	u32 bit, reg;
339 	const struct aspeed_sgpio_bank *bank;
340 	irq_flow_handler_t handler;
341 	struct aspeed_sgpio *gpio;
342 	unsigned long flags;
343 	void __iomem *addr;
344 	int offset;
345 
346 	irqd_to_aspeed_sgpio_data(d, &gpio, &bank, &bit, &offset);
347 
348 	switch (type & IRQ_TYPE_SENSE_MASK) {
349 	case IRQ_TYPE_EDGE_BOTH:
350 		type2 |= bit;
351 		fallthrough;
352 	case IRQ_TYPE_EDGE_RISING:
353 		type0 |= bit;
354 		fallthrough;
355 	case IRQ_TYPE_EDGE_FALLING:
356 		handler = handle_edge_irq;
357 		break;
358 	case IRQ_TYPE_LEVEL_HIGH:
359 		type0 |= bit;
360 		fallthrough;
361 	case IRQ_TYPE_LEVEL_LOW:
362 		type1 |= bit;
363 		handler = handle_level_irq;
364 		break;
365 	default:
366 		return -EINVAL;
367 	}
368 
369 	raw_spin_lock_irqsave(&gpio->lock, flags);
370 
371 	addr = bank_reg(gpio, bank, reg_irq_type0);
372 	reg = ioread32(addr);
373 	reg = (reg & ~bit) | type0;
374 	iowrite32(reg, addr);
375 
376 	addr = bank_reg(gpio, bank, reg_irq_type1);
377 	reg = ioread32(addr);
378 	reg = (reg & ~bit) | type1;
379 	iowrite32(reg, addr);
380 
381 	addr = bank_reg(gpio, bank, reg_irq_type2);
382 	reg = ioread32(addr);
383 	reg = (reg & ~bit) | type2;
384 	iowrite32(reg, addr);
385 
386 	raw_spin_unlock_irqrestore(&gpio->lock, flags);
387 
388 	irq_set_handler_locked(d, handler);
389 
390 	return 0;
391 }
392 
aspeed_sgpio_irq_handler(struct irq_desc * desc)393 static void aspeed_sgpio_irq_handler(struct irq_desc *desc)
394 {
395 	struct gpio_chip *gc = irq_desc_get_handler_data(desc);
396 	struct irq_chip *ic = irq_desc_get_chip(desc);
397 	struct aspeed_sgpio *data = gpiochip_get_data(gc);
398 	unsigned int i, p;
399 	unsigned long reg;
400 
401 	chained_irq_enter(ic, desc);
402 
403 	for (i = 0; i < ARRAY_SIZE(aspeed_sgpio_banks); i++) {
404 		const struct aspeed_sgpio_bank *bank = &aspeed_sgpio_banks[i];
405 
406 		reg = ioread32(bank_reg(data, bank, reg_irq_status));
407 
408 		for_each_set_bit(p, &reg, 32)
409 			generic_handle_domain_irq(gc->irq.domain, (i * 32 + p) * 2);
410 	}
411 
412 	chained_irq_exit(ic, desc);
413 }
414 
aspeed_sgpio_irq_print_chip(struct irq_data * d,struct seq_file * p)415 static void aspeed_sgpio_irq_print_chip(struct irq_data *d, struct seq_file *p)
416 {
417 	const struct aspeed_sgpio_bank *bank;
418 	struct aspeed_sgpio *gpio;
419 	u32 bit;
420 	int offset;
421 
422 	irqd_to_aspeed_sgpio_data(d, &gpio, &bank, &bit, &offset);
423 	seq_printf(p, dev_name(gpio->dev));
424 }
425 
426 static const struct irq_chip aspeed_sgpio_irq_chip = {
427 	.irq_ack = aspeed_sgpio_irq_ack,
428 	.irq_mask = aspeed_sgpio_irq_mask,
429 	.irq_unmask = aspeed_sgpio_irq_unmask,
430 	.irq_set_type = aspeed_sgpio_set_type,
431 	.irq_print_chip = aspeed_sgpio_irq_print_chip,
432 	.flags = IRQCHIP_IMMUTABLE,
433 	GPIOCHIP_IRQ_RESOURCE_HELPERS,
434 };
435 
aspeed_sgpio_setup_irqs(struct aspeed_sgpio * gpio,struct platform_device * pdev)436 static int aspeed_sgpio_setup_irqs(struct aspeed_sgpio *gpio,
437 				   struct platform_device *pdev)
438 {
439 	int rc, i;
440 	const struct aspeed_sgpio_bank *bank;
441 	struct gpio_irq_chip *irq;
442 
443 	rc = platform_get_irq(pdev, 0);
444 	if (rc < 0)
445 		return rc;
446 
447 	gpio->irq = rc;
448 
449 	/* Disable IRQ and clear Interrupt status registers for all SGPIO Pins. */
450 	for (i = 0; i < ARRAY_SIZE(aspeed_sgpio_banks); i++) {
451 		bank =  &aspeed_sgpio_banks[i];
452 		/* disable irq enable bits */
453 		iowrite32(0x00000000, bank_reg(gpio, bank, reg_irq_enable));
454 		/* clear status bits */
455 		iowrite32(0xffffffff, bank_reg(gpio, bank, reg_irq_status));
456 	}
457 
458 	irq = &gpio->chip.irq;
459 	gpio_irq_chip_set_chip(irq, &aspeed_sgpio_irq_chip);
460 	irq->init_valid_mask = aspeed_sgpio_irq_init_valid_mask;
461 	irq->handler = handle_bad_irq;
462 	irq->default_type = IRQ_TYPE_NONE;
463 	irq->parent_handler = aspeed_sgpio_irq_handler;
464 	irq->parent_handler_data = gpio;
465 	irq->parents = &gpio->irq;
466 	irq->num_parents = 1;
467 
468 	/* Apply default IRQ settings */
469 	for (i = 0; i < ARRAY_SIZE(aspeed_sgpio_banks); i++) {
470 		bank = &aspeed_sgpio_banks[i];
471 		/* set falling or level-low irq */
472 		iowrite32(0x00000000, bank_reg(gpio, bank, reg_irq_type0));
473 		/* trigger type is edge */
474 		iowrite32(0x00000000, bank_reg(gpio, bank, reg_irq_type1));
475 		/* single edge trigger */
476 		iowrite32(0x00000000, bank_reg(gpio, bank, reg_irq_type2));
477 	}
478 
479 	return 0;
480 }
481 
482 static const struct aspeed_sgpio_pdata ast2400_sgpio_pdata = {
483 	.pin_mask = GENMASK(9, 6),
484 };
485 
aspeed_sgpio_reset_tolerance(struct gpio_chip * chip,unsigned int offset,bool enable)486 static int aspeed_sgpio_reset_tolerance(struct gpio_chip *chip,
487 					unsigned int offset, bool enable)
488 {
489 	struct aspeed_sgpio *gpio = gpiochip_get_data(chip);
490 	unsigned long flags;
491 	void __iomem *reg;
492 	u32 val;
493 
494 	reg = bank_reg(gpio, to_bank(offset), reg_tolerance);
495 
496 	raw_spin_lock_irqsave(&gpio->lock, flags);
497 
498 	val = readl(reg);
499 
500 	if (enable)
501 		val |= GPIO_BIT(offset);
502 	else
503 		val &= ~GPIO_BIT(offset);
504 
505 	writel(val, reg);
506 
507 	raw_spin_unlock_irqrestore(&gpio->lock, flags);
508 
509 	return 0;
510 }
511 
aspeed_sgpio_set_config(struct gpio_chip * chip,unsigned int offset,unsigned long config)512 static int aspeed_sgpio_set_config(struct gpio_chip *chip, unsigned int offset,
513 				   unsigned long config)
514 {
515 	unsigned long param = pinconf_to_config_param(config);
516 	u32 arg = pinconf_to_config_argument(config);
517 
518 	if (param == PIN_CONFIG_PERSIST_STATE)
519 		return aspeed_sgpio_reset_tolerance(chip, offset, arg);
520 
521 	return -ENOTSUPP;
522 }
523 
524 static const struct aspeed_sgpio_pdata ast2600_sgpiom_pdata = {
525 	.pin_mask = GENMASK(10, 6),
526 };
527 
528 static const struct of_device_id aspeed_sgpio_of_table[] = {
529 	{ .compatible = "aspeed,ast2400-sgpio", .data = &ast2400_sgpio_pdata, },
530 	{ .compatible = "aspeed,ast2500-sgpio", .data = &ast2400_sgpio_pdata, },
531 	{ .compatible = "aspeed,ast2600-sgpiom", .data = &ast2600_sgpiom_pdata, },
532 	{}
533 };
534 
535 MODULE_DEVICE_TABLE(of, aspeed_sgpio_of_table);
536 
aspeed_sgpio_probe(struct platform_device * pdev)537 static int __init aspeed_sgpio_probe(struct platform_device *pdev)
538 {
539 	u32 nr_gpios, sgpio_freq, sgpio_clk_div, gpio_cnt_regval, pin_mask;
540 	const struct aspeed_sgpio_pdata *pdata;
541 	struct aspeed_sgpio *gpio;
542 	unsigned long apb_freq;
543 	int rc;
544 
545 	gpio = devm_kzalloc(&pdev->dev, sizeof(*gpio), GFP_KERNEL);
546 	if (!gpio)
547 		return -ENOMEM;
548 
549 	gpio->base = devm_platform_ioremap_resource(pdev, 0);
550 	if (IS_ERR(gpio->base))
551 		return PTR_ERR(gpio->base);
552 
553 	gpio->dev = &pdev->dev;
554 
555 	pdata = device_get_match_data(&pdev->dev);
556 	if (!pdata)
557 		return -EINVAL;
558 
559 	pin_mask = pdata->pin_mask;
560 
561 	rc = device_property_read_u32(&pdev->dev, "ngpios", &nr_gpios);
562 	if (rc < 0) {
563 		dev_err(&pdev->dev, "Could not read ngpios property\n");
564 		return -EINVAL;
565 	} else if (nr_gpios % 8) {
566 		dev_err(&pdev->dev, "Number of GPIOs not multiple of 8: %d\n",
567 			nr_gpios);
568 		return -EINVAL;
569 	}
570 
571 	rc = device_property_read_u32(&pdev->dev, "bus-frequency", &sgpio_freq);
572 	if (rc < 0) {
573 		dev_err(&pdev->dev, "Could not read bus-frequency property\n");
574 		return -EINVAL;
575 	}
576 
577 	gpio->pclk = devm_clk_get(&pdev->dev, NULL);
578 	if (IS_ERR(gpio->pclk)) {
579 		dev_err(&pdev->dev, "devm_clk_get failed\n");
580 		return PTR_ERR(gpio->pclk);
581 	}
582 
583 	apb_freq = clk_get_rate(gpio->pclk);
584 
585 	/*
586 	 * From the datasheet,
587 	 *	SGPIO period = 1/PCLK * 2 * (GPIO254[31:16] + 1)
588 	 *	period = 2 * (GPIO254[31:16] + 1) / PCLK
589 	 *	frequency = 1 / (2 * (GPIO254[31:16] + 1) / PCLK)
590 	 *	frequency = PCLK / (2 * (GPIO254[31:16] + 1))
591 	 *	frequency * 2 * (GPIO254[31:16] + 1) = PCLK
592 	 *	GPIO254[31:16] = PCLK / (frequency * 2) - 1
593 	 */
594 	if (sgpio_freq == 0)
595 		return -EINVAL;
596 
597 	sgpio_clk_div = (apb_freq / (sgpio_freq * 2)) - 1;
598 
599 	if (sgpio_clk_div > (1 << 16) - 1)
600 		return -EINVAL;
601 
602 	gpio_cnt_regval = ((nr_gpios / 8) << ASPEED_SGPIO_PINS_SHIFT) & pin_mask;
603 	iowrite32(FIELD_PREP(ASPEED_SGPIO_CLK_DIV_MASK, sgpio_clk_div) | gpio_cnt_regval |
604 		  ASPEED_SGPIO_ENABLE, gpio->base + ASPEED_SGPIO_CTRL);
605 
606 	raw_spin_lock_init(&gpio->lock);
607 
608 	gpio->chip.parent = &pdev->dev;
609 	gpio->chip.ngpio = nr_gpios * 2;
610 	gpio->chip.init_valid_mask = aspeed_sgpio_init_valid_mask;
611 	gpio->chip.direction_input = aspeed_sgpio_dir_in;
612 	gpio->chip.direction_output = aspeed_sgpio_dir_out;
613 	gpio->chip.get_direction = aspeed_sgpio_get_direction;
614 	gpio->chip.request = NULL;
615 	gpio->chip.free = NULL;
616 	gpio->chip.get = aspeed_sgpio_get;
617 	gpio->chip.set = aspeed_sgpio_set;
618 	gpio->chip.set_config = aspeed_sgpio_set_config;
619 	gpio->chip.label = dev_name(&pdev->dev);
620 	gpio->chip.base = -1;
621 
622 	aspeed_sgpio_setup_irqs(gpio, pdev);
623 
624 	rc = devm_gpiochip_add_data(&pdev->dev, &gpio->chip, gpio);
625 	if (rc < 0)
626 		return rc;
627 
628 	return 0;
629 }
630 
631 static struct platform_driver aspeed_sgpio_driver = {
632 	.driver = {
633 		.name = KBUILD_MODNAME,
634 		.of_match_table = aspeed_sgpio_of_table,
635 	},
636 };
637 
638 module_platform_driver_probe(aspeed_sgpio_driver, aspeed_sgpio_probe);
639 MODULE_DESCRIPTION("Aspeed Serial GPIO Driver");
640