brintos

brintos / linux-shallow public Read only

0
0
Text · 17.0 KiB · 75eadda Raw
549 lines · c
1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Copyright (C) 2021 Aspeed Technology Inc.4 *5 * PWM/TACH controller driver for Aspeed ast2600 SoCs.6 * This drivers doesn't support earlier version of the IP.7 *8 * The hardware operates in time quantities of length9 * Q := (DIV_L + 1) << DIV_H / input-clk10 * The length of a PWM period is (DUTY_CYCLE_PERIOD + 1) * Q.11 * The maximal value for DUTY_CYCLE_PERIOD is used here to provide12 * a fine grained selection for the duty cycle.13 *14 * This driver uses DUTY_CYCLE_RISING_POINT = 0, so from the start of a15 * period the output is active until DUTY_CYCLE_FALLING_POINT * Q. Note16 * that if DUTY_CYCLE_RISING_POINT = DUTY_CYCLE_FALLING_POINT the output is17 * always active.18 *19 * Register usage:20 * PIN_ENABLE: When it is unset the pwm controller will emit inactive level to the external.21 * Use to determine whether the PWM channel is enabled or disabled22 * CLK_ENABLE: When it is unset the pwm controller will assert the duty counter reset and23 * emit inactive level to the PIN_ENABLE mux after that the driver can still change the pwm period24 * and duty and the value will apply when CLK_ENABLE be set again.25 * Use to determine whether duty_cycle bigger than 0.26 * PWM_ASPEED_CTRL_INVERSE: When it is toggled the output value will inverse immediately.27 * PWM_ASPEED_DUTY_CYCLE_FALLING_POINT/PWM_ASPEED_DUTY_CYCLE_RISING_POINT: When these two28 * values are equal it means the duty cycle = 100%.29 *30 * The glitch may generate at:31 * - Enabled changing when the duty_cycle bigger than 0% and less than 100%.32 * - Polarity changing when the duty_cycle bigger than 0% and less than 100%.33 *34 * Limitations:35 * - When changing both duty cycle and period, we cannot prevent in36 *   software that the output might produce a period with mixed37 *   settings.38 * - Disabling the PWM doesn't complete the current period.39 *40 * Improvements:41 * - When only changing one of duty cycle or period, our pwm controller will not42 *   generate the glitch, the configure will change at next cycle of pwm.43 *   This improvement can disable/enable through PWM_ASPEED_CTRL_DUTY_SYNC_DISABLE.44 */45 46#include <linux/bitfield.h>47#include <linux/clk.h>48#include <linux/delay.h>49#include <linux/errno.h>50#include <linux/hwmon.h>51#include <linux/io.h>52#include <linux/kernel.h>53#include <linux/math64.h>54#include <linux/module.h>55#include <linux/of_device.h>56#include <linux/of_platform.h>57#include <linux/platform_device.h>58#include <linux/pwm.h>59#include <linux/reset.h>60#include <linux/sysfs.h>61 62/* The channel number of Aspeed pwm controller */63#define PWM_ASPEED_NR_PWMS			1664/* PWM Control Register */65#define PWM_ASPEED_CTRL(ch)			((ch) * 0x10 + 0x00)66#define PWM_ASPEED_CTRL_LOAD_SEL_RISING_AS_WDT	BIT(19)67#define PWM_ASPEED_CTRL_DUTY_LOAD_AS_WDT_ENABLE	BIT(18)68#define PWM_ASPEED_CTRL_DUTY_SYNC_DISABLE	BIT(17)69#define PWM_ASPEED_CTRL_CLK_ENABLE		BIT(16)70#define PWM_ASPEED_CTRL_LEVEL_OUTPUT		BIT(15)71#define PWM_ASPEED_CTRL_INVERSE			BIT(14)72#define PWM_ASPEED_CTRL_OPEN_DRAIN_ENABLE	BIT(13)73#define PWM_ASPEED_CTRL_PIN_ENABLE		BIT(12)74#define PWM_ASPEED_CTRL_CLK_DIV_H		GENMASK(11, 8)75#define PWM_ASPEED_CTRL_CLK_DIV_L		GENMASK(7, 0)76 77/* PWM Duty Cycle Register */78#define PWM_ASPEED_DUTY_CYCLE(ch)		((ch) * 0x10 + 0x04)79#define PWM_ASPEED_DUTY_CYCLE_PERIOD		GENMASK(31, 24)80#define PWM_ASPEED_DUTY_CYCLE_POINT_AS_WDT	GENMASK(23, 16)81#define PWM_ASPEED_DUTY_CYCLE_FALLING_POINT	GENMASK(15, 8)82#define PWM_ASPEED_DUTY_CYCLE_RISING_POINT	GENMASK(7, 0)83 84/* PWM fixed value */85#define PWM_ASPEED_FIXED_PERIOD			FIELD_MAX(PWM_ASPEED_DUTY_CYCLE_PERIOD)86 87/* The channel number of Aspeed tach controller */88#define TACH_ASPEED_NR_TACHS		1689/* TACH Control Register */90#define TACH_ASPEED_CTRL(ch)		(((ch) * 0x10) + 0x08)91#define TACH_ASPEED_IER			BIT(31)92#define TACH_ASPEED_INVERS_LIMIT	BIT(30)93#define TACH_ASPEED_LOOPBACK		BIT(29)94#define TACH_ASPEED_ENABLE		BIT(28)95#define TACH_ASPEED_DEBOUNCE_MASK	GENMASK(27, 26)96#define TACH_ASPEED_DEBOUNCE_BIT	2697#define TACH_ASPEED_IO_EDGE_MASK	GENMASK(25, 24)98#define TACH_ASPEED_IO_EDGE_BIT		2499#define TACH_ASPEED_CLK_DIV_T_MASK	GENMASK(23, 20)100#define TACH_ASPEED_CLK_DIV_BIT		20101#define TACH_ASPEED_THRESHOLD_MASK	GENMASK(19, 0)102/* [27:26] */103#define DEBOUNCE_3_CLK			0x00104#define DEBOUNCE_2_CLK			0x01105#define DEBOUNCE_1_CLK			0x02106#define DEBOUNCE_0_CLK			0x03107/* [25:24] */108#define F2F_EDGES			0x00109#define R2R_EDGES			0x01110#define BOTH_EDGES			0x02111/* [23:20] */112/* divisor = 4 to the nth power, n = register value */113#define DEFAULT_TACH_DIV		1024114#define DIV_TO_REG(divisor)		(ilog2(divisor) >> 1)115 116/* TACH Status Register */117#define TACH_ASPEED_STS(ch)		(((ch) * 0x10) + 0x0C)118 119/*PWM_TACH_STS */120#define TACH_ASPEED_ISR			BIT(31)121#define TACH_ASPEED_PWM_OUT		BIT(25)122#define TACH_ASPEED_PWM_OEN		BIT(24)123#define TACH_ASPEED_DEB_INPUT		BIT(23)124#define TACH_ASPEED_RAW_INPUT		BIT(22)125#define TACH_ASPEED_VALUE_UPDATE	BIT(21)126#define TACH_ASPEED_FULL_MEASUREMENT	BIT(20)127#define TACH_ASPEED_VALUE_MASK		GENMASK(19, 0)128/**********************************************************129 * Software setting130 *********************************************************/131#define DEFAULT_FAN_PULSE_PR		2132 133struct aspeed_pwm_tach_data {134	struct device *dev;135	void __iomem *base;136	struct clk *clk;137	struct reset_control *reset;138	unsigned long clk_rate;139	bool tach_present[TACH_ASPEED_NR_TACHS];140	u32 tach_divisor;141};142 143static inline struct aspeed_pwm_tach_data *144aspeed_pwm_chip_to_data(struct pwm_chip *chip)145{146	return pwmchip_get_drvdata(chip);147}148 149static int aspeed_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,150				struct pwm_state *state)151{152	struct aspeed_pwm_tach_data *priv = aspeed_pwm_chip_to_data(chip);153	u32 hwpwm = pwm->hwpwm;154	bool polarity, pin_en, clk_en;155	u32 duty_pt, val;156	u64 div_h, div_l, duty_cycle_period, dividend;157 158	val = readl(priv->base + PWM_ASPEED_CTRL(hwpwm));159	polarity = FIELD_GET(PWM_ASPEED_CTRL_INVERSE, val);160	pin_en = FIELD_GET(PWM_ASPEED_CTRL_PIN_ENABLE, val);161	clk_en = FIELD_GET(PWM_ASPEED_CTRL_CLK_ENABLE, val);162	div_h = FIELD_GET(PWM_ASPEED_CTRL_CLK_DIV_H, val);163	div_l = FIELD_GET(PWM_ASPEED_CTRL_CLK_DIV_L, val);164	val = readl(priv->base + PWM_ASPEED_DUTY_CYCLE(hwpwm));165	duty_pt = FIELD_GET(PWM_ASPEED_DUTY_CYCLE_FALLING_POINT, val);166	duty_cycle_period = FIELD_GET(PWM_ASPEED_DUTY_CYCLE_PERIOD, val);167	/*168	 * This multiplication doesn't overflow, the upper bound is169	 * 1000000000 * 256 * 256 << 15 = 0x1dcd650000000000170	 */171	dividend = (u64)NSEC_PER_SEC * (div_l + 1) * (duty_cycle_period + 1)172		       << div_h;173	state->period = DIV_ROUND_UP_ULL(dividend, priv->clk_rate);174 175	if (clk_en && duty_pt) {176		dividend = (u64)NSEC_PER_SEC * (div_l + 1) * duty_pt177				 << div_h;178		state->duty_cycle = DIV_ROUND_UP_ULL(dividend, priv->clk_rate);179	} else {180		state->duty_cycle = clk_en ? state->period : 0;181	}182	state->polarity = polarity ? PWM_POLARITY_INVERSED : PWM_POLARITY_NORMAL;183	state->enabled = pin_en;184	return 0;185}186 187static int aspeed_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,188			    const struct pwm_state *state)189{190	struct aspeed_pwm_tach_data *priv = aspeed_pwm_chip_to_data(chip);191	u32 hwpwm = pwm->hwpwm, duty_pt, val;192	u64 div_h, div_l, divisor, expect_period;193	bool clk_en;194 195	expect_period = div64_u64(ULLONG_MAX, (u64)priv->clk_rate);196	expect_period = min(expect_period, state->period);197	dev_dbg(pwmchip_parent(chip), "expect period: %lldns, duty_cycle: %lldns",198		expect_period, state->duty_cycle);199	/*200	 * Pick the smallest value for div_h so that div_l can be the biggest201	 * which results in a finer resolution near the target period value.202	 */203	divisor = (u64)NSEC_PER_SEC * (PWM_ASPEED_FIXED_PERIOD + 1) *204		  (FIELD_MAX(PWM_ASPEED_CTRL_CLK_DIV_L) + 1);205	div_h = order_base_2(DIV64_U64_ROUND_UP(priv->clk_rate * expect_period, divisor));206	if (div_h > 0xf)207		div_h = 0xf;208 209	divisor = ((u64)NSEC_PER_SEC * (PWM_ASPEED_FIXED_PERIOD + 1)) << div_h;210	div_l = div64_u64(priv->clk_rate * expect_period, divisor);211 212	if (div_l == 0)213		return -ERANGE;214 215	div_l -= 1;216 217	if (div_l > 255)218		div_l = 255;219 220	dev_dbg(pwmchip_parent(chip), "clk source: %ld div_h %lld, div_l : %lld\n",221		priv->clk_rate, div_h, div_l);222	/* duty_pt = duty_cycle * (PERIOD + 1) / period */223	duty_pt = div64_u64(state->duty_cycle * priv->clk_rate,224			    (u64)NSEC_PER_SEC * (div_l + 1) << div_h);225	dev_dbg(pwmchip_parent(chip), "duty_cycle = %lld, duty_pt = %d\n",226		state->duty_cycle, duty_pt);227 228	/*229	 * Fixed DUTY_CYCLE_PERIOD to its max value to get a230	 * fine-grained resolution for duty_cycle at the expense of a231	 * coarser period resolution.232	 */233	val = readl(priv->base + PWM_ASPEED_DUTY_CYCLE(hwpwm));234	val &= ~PWM_ASPEED_DUTY_CYCLE_PERIOD;235	val |= FIELD_PREP(PWM_ASPEED_DUTY_CYCLE_PERIOD,236			  PWM_ASPEED_FIXED_PERIOD);237	writel(val, priv->base + PWM_ASPEED_DUTY_CYCLE(hwpwm));238 239	if (duty_pt == 0) {240		/* emit inactive level and assert the duty counter reset */241		clk_en = 0;242	} else {243		clk_en = 1;244		if (duty_pt >= (PWM_ASPEED_FIXED_PERIOD + 1))245			duty_pt = 0;246		val = readl(priv->base + PWM_ASPEED_DUTY_CYCLE(hwpwm));247		val &= ~(PWM_ASPEED_DUTY_CYCLE_RISING_POINT |248			 PWM_ASPEED_DUTY_CYCLE_FALLING_POINT);249		val |= FIELD_PREP(PWM_ASPEED_DUTY_CYCLE_FALLING_POINT, duty_pt);250		writel(val, priv->base + PWM_ASPEED_DUTY_CYCLE(hwpwm));251	}252 253	val = readl(priv->base + PWM_ASPEED_CTRL(hwpwm));254	val &= ~(PWM_ASPEED_CTRL_CLK_DIV_H | PWM_ASPEED_CTRL_CLK_DIV_L |255		 PWM_ASPEED_CTRL_PIN_ENABLE | PWM_ASPEED_CTRL_CLK_ENABLE |256		 PWM_ASPEED_CTRL_INVERSE);257	val |= FIELD_PREP(PWM_ASPEED_CTRL_CLK_DIV_H, div_h) |258	       FIELD_PREP(PWM_ASPEED_CTRL_CLK_DIV_L, div_l) |259	       FIELD_PREP(PWM_ASPEED_CTRL_PIN_ENABLE, state->enabled) |260	       FIELD_PREP(PWM_ASPEED_CTRL_CLK_ENABLE, clk_en) |261	       FIELD_PREP(PWM_ASPEED_CTRL_INVERSE, state->polarity);262	writel(val, priv->base + PWM_ASPEED_CTRL(hwpwm));263 264	return 0;265}266 267static const struct pwm_ops aspeed_pwm_ops = {268	.apply = aspeed_pwm_apply,269	.get_state = aspeed_pwm_get_state,270};271 272static void aspeed_tach_ch_enable(struct aspeed_pwm_tach_data *priv, u8 tach_ch,273				  bool enable)274{275	if (enable)276		writel(readl(priv->base + TACH_ASPEED_CTRL(tach_ch)) |277			       TACH_ASPEED_ENABLE,278		       priv->base + TACH_ASPEED_CTRL(tach_ch));279	else280		writel(readl(priv->base + TACH_ASPEED_CTRL(tach_ch)) &281			       ~TACH_ASPEED_ENABLE,282		       priv->base + TACH_ASPEED_CTRL(tach_ch));283}284 285static int aspeed_tach_val_to_rpm(struct aspeed_pwm_tach_data *priv, u32 tach_val)286{287	u64 rpm;288	u32 tach_div;289 290	tach_div = tach_val * priv->tach_divisor * DEFAULT_FAN_PULSE_PR;291 292	dev_dbg(priv->dev, "clk %ld, tach_val %d , tach_div %d\n",293		priv->clk_rate, tach_val, tach_div);294 295	rpm = (u64)priv->clk_rate * 60;296	do_div(rpm, tach_div);297 298	return (int)rpm;299}300 301static int aspeed_get_fan_tach_ch_rpm(struct aspeed_pwm_tach_data *priv,302				      u8 fan_tach_ch)303{304	u32 val;305 306	val = readl(priv->base + TACH_ASPEED_STS(fan_tach_ch));307 308	if (!(val & TACH_ASPEED_FULL_MEASUREMENT))309		return 0;310	val = FIELD_GET(TACH_ASPEED_VALUE_MASK, val);311	return aspeed_tach_val_to_rpm(priv, val);312}313 314static int aspeed_tach_hwmon_read(struct device *dev,315				  enum hwmon_sensor_types type, u32 attr,316				  int channel, long *val)317{318	struct aspeed_pwm_tach_data *priv = dev_get_drvdata(dev);319	u32 reg_val;320 321	switch (attr) {322	case hwmon_fan_input:323		*val = aspeed_get_fan_tach_ch_rpm(priv, channel);324		break;325	case hwmon_fan_div:326		reg_val = readl(priv->base + TACH_ASPEED_CTRL(channel));327		reg_val = FIELD_GET(TACH_ASPEED_CLK_DIV_T_MASK, reg_val);328		*val = BIT(reg_val << 1);329		break;330	default:331		return -EOPNOTSUPP;332	}333	return 0;334}335 336static int aspeed_tach_hwmon_write(struct device *dev,337				   enum hwmon_sensor_types type, u32 attr,338				   int channel, long val)339{340	struct aspeed_pwm_tach_data *priv = dev_get_drvdata(dev);341	u32 reg_val;342 343	switch (attr) {344	case hwmon_fan_div:345		if (!is_power_of_2(val) || (ilog2(val) % 2) ||346		    DIV_TO_REG(val) > 0xb)347			return -EINVAL;348		priv->tach_divisor = val;349		reg_val = readl(priv->base + TACH_ASPEED_CTRL(channel));350		reg_val &= ~TACH_ASPEED_CLK_DIV_T_MASK;351		reg_val |= FIELD_PREP(TACH_ASPEED_CLK_DIV_T_MASK,352				      DIV_TO_REG(priv->tach_divisor));353		writel(reg_val, priv->base + TACH_ASPEED_CTRL(channel));354		break;355	default:356		return -EOPNOTSUPP;357	}358 359	return 0;360}361 362static umode_t aspeed_tach_dev_is_visible(const void *drvdata,363					  enum hwmon_sensor_types type,364					  u32 attr, int channel)365{366	const struct aspeed_pwm_tach_data *priv = drvdata;367 368	if (!priv->tach_present[channel])369		return 0;370	switch (attr) {371	case hwmon_fan_input:372		return 0444;373	case hwmon_fan_div:374		return 0644;375	}376	return 0;377}378 379static const struct hwmon_ops aspeed_tach_ops = {380	.is_visible = aspeed_tach_dev_is_visible,381	.read = aspeed_tach_hwmon_read,382	.write = aspeed_tach_hwmon_write,383};384 385static const struct hwmon_channel_info *aspeed_tach_info[] = {386	HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT | HWMON_F_DIV, HWMON_F_INPUT | HWMON_F_DIV,387			   HWMON_F_INPUT | HWMON_F_DIV, HWMON_F_INPUT | HWMON_F_DIV,388			   HWMON_F_INPUT | HWMON_F_DIV, HWMON_F_INPUT | HWMON_F_DIV,389			   HWMON_F_INPUT | HWMON_F_DIV, HWMON_F_INPUT | HWMON_F_DIV,390			   HWMON_F_INPUT | HWMON_F_DIV, HWMON_F_INPUT | HWMON_F_DIV,391			   HWMON_F_INPUT | HWMON_F_DIV, HWMON_F_INPUT | HWMON_F_DIV,392			   HWMON_F_INPUT | HWMON_F_DIV, HWMON_F_INPUT | HWMON_F_DIV,393			   HWMON_F_INPUT | HWMON_F_DIV, HWMON_F_INPUT | HWMON_F_DIV),394	NULL395};396 397static const struct hwmon_chip_info aspeed_tach_chip_info = {398	.ops = &aspeed_tach_ops,399	.info = aspeed_tach_info,400};401 402static void aspeed_present_fan_tach(struct aspeed_pwm_tach_data *priv, u8 *tach_ch, int count)403{404	u8 ch, index;405	u32 val;406 407	for (index = 0; index < count; index++) {408		ch = tach_ch[index];409		priv->tach_present[ch] = true;410		priv->tach_divisor = DEFAULT_TACH_DIV;411 412		val = readl(priv->base + TACH_ASPEED_CTRL(ch));413		val &= ~(TACH_ASPEED_INVERS_LIMIT | TACH_ASPEED_DEBOUNCE_MASK |414			 TACH_ASPEED_IO_EDGE_MASK | TACH_ASPEED_CLK_DIV_T_MASK |415			 TACH_ASPEED_THRESHOLD_MASK);416		val |= (DEBOUNCE_3_CLK << TACH_ASPEED_DEBOUNCE_BIT) |417		       F2F_EDGES |418		       FIELD_PREP(TACH_ASPEED_CLK_DIV_T_MASK,419				  DIV_TO_REG(priv->tach_divisor));420		writel(val, priv->base + TACH_ASPEED_CTRL(ch));421 422		aspeed_tach_ch_enable(priv, ch, true);423	}424}425 426static int aspeed_create_fan_monitor(struct device *dev,427				     struct device_node *child,428				     struct aspeed_pwm_tach_data *priv)429{430	int ret, count;431	u8 *tach_ch;432 433	count = of_property_count_u8_elems(child, "tach-ch");434	if (count < 1)435		return -EINVAL;436	tach_ch = devm_kcalloc(dev, count, sizeof(*tach_ch), GFP_KERNEL);437	if (!tach_ch)438		return -ENOMEM;439	ret = of_property_read_u8_array(child, "tach-ch", tach_ch, count);440	if (ret)441		return ret;442 443	aspeed_present_fan_tach(priv, tach_ch, count);444 445	return 0;446}447 448static void aspeed_pwm_tach_reset_assert(void *data)449{450	struct reset_control *rst = data;451 452	reset_control_assert(rst);453}454 455static int aspeed_pwm_tach_probe(struct platform_device *pdev)456{457	struct device *dev = &pdev->dev, *hwmon;458	int ret;459	struct aspeed_pwm_tach_data *priv;460	struct pwm_chip *chip;461 462	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);463	if (!priv)464		return -ENOMEM;465	priv->dev = dev;466	priv->base = devm_platform_ioremap_resource(pdev, 0);467	if (IS_ERR(priv->base))468		return PTR_ERR(priv->base);469 470	priv->clk = devm_clk_get_enabled(dev, NULL);471	if (IS_ERR(priv->clk))472		return dev_err_probe(dev, PTR_ERR(priv->clk),473				     "Couldn't get clock\n");474	priv->clk_rate = clk_get_rate(priv->clk);475	priv->reset = devm_reset_control_get_exclusive(dev, NULL);476	if (IS_ERR(priv->reset))477		return dev_err_probe(dev, PTR_ERR(priv->reset),478				     "Couldn't get reset control\n");479 480	ret = reset_control_deassert(priv->reset);481	if (ret)482		return dev_err_probe(dev, ret,483				     "Couldn't deassert reset control\n");484	ret = devm_add_action_or_reset(dev, aspeed_pwm_tach_reset_assert,485				       priv->reset);486	if (ret)487		return ret;488 489	chip = devm_pwmchip_alloc(dev, PWM_ASPEED_NR_PWMS, 0);490	if (IS_ERR(chip))491		return PTR_ERR(chip);492 493	pwmchip_set_drvdata(chip, priv);494	chip->ops = &aspeed_pwm_ops;495 496	ret = devm_pwmchip_add(dev, chip);497	if (ret)498		return dev_err_probe(dev, ret, "Failed to add PWM chip\n");499 500	for_each_child_of_node_scoped(dev->of_node, child) {501		ret = aspeed_create_fan_monitor(dev, child, priv);502		if (ret) {503			dev_warn(dev, "Failed to create fan %d", ret);504			return 0;505		}506	}507 508	hwmon = devm_hwmon_device_register_with_info(dev, "aspeed_tach", priv,509						     &aspeed_tach_chip_info, NULL);510	ret = PTR_ERR_OR_ZERO(hwmon);511	if (ret)512		return dev_err_probe(dev, ret,513				     "Failed to register hwmon device\n");514 515	of_platform_populate(dev->of_node, NULL, NULL, dev);516 517	return 0;518}519 520static void aspeed_pwm_tach_remove(struct platform_device *pdev)521{522	struct aspeed_pwm_tach_data *priv = platform_get_drvdata(pdev);523 524	reset_control_assert(priv->reset);525}526 527static const struct of_device_id aspeed_pwm_tach_match[] = {528	{529		.compatible = "aspeed,ast2600-pwm-tach",530	},531	{},532};533MODULE_DEVICE_TABLE(of, aspeed_pwm_tach_match);534 535static struct platform_driver aspeed_pwm_tach_driver = {536	.probe = aspeed_pwm_tach_probe,537	.remove_new = aspeed_pwm_tach_remove,538	.driver	= {539		.name = "aspeed-g6-pwm-tach",540		.of_match_table = aspeed_pwm_tach_match,541	},542};543 544module_platform_driver(aspeed_pwm_tach_driver);545 546MODULE_AUTHOR("Billy Tsai <billy_tsai@aspeedtech.com>");547MODULE_DESCRIPTION("Aspeed ast2600 PWM and Fan Tach device driver");548MODULE_LICENSE("GPL");549