1// SPDX-License-Identifier: GPL-2.0
2/*
3 * STM32 Low-Power Timer parent driver.
4 * Copyright (C) STMicroelectronics 2017
5 * Author: Fabrice Gasnier <fabrice.gasnier@st.com>
6 * Inspired by Benjamin Gaignard's stm32-timers driver
7 */
8
9#include <linux/mfd/stm32-lptimer.h>
10#include <linux/module.h>
11#include <linux/of_platform.h>
12#include <linux/platform_device.h>
13
14#define STM32_LPTIM_MAX_REGISTER	0x3fc
15
16static const struct regmap_config stm32_lptimer_regmap_cfg = {
17	.reg_bits = 32,
18	.val_bits = 32,
19	.reg_stride = sizeof(u32),
20	.max_register = STM32_LPTIM_MAX_REGISTER,
21	.fast_io = true,
22};
23
24static int stm32_lptimer_detect_encoder(struct stm32_lptimer *ddata)
25{
26	u32 val;
27	int ret;
28
29	/*
30	 * Quadrature encoder mode bit can only be written and read back when
31	 * Low-Power Timer supports it.
32	 */
33	ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,
34				 STM32_LPTIM_ENC, STM32_LPTIM_ENC);
35	if (ret)
36		return ret;
37
38	ret = regmap_read(ddata->regmap, STM32_LPTIM_CFGR, &val);
39	if (ret)
40		return ret;
41
42	ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,
43				 STM32_LPTIM_ENC, 0);
44	if (ret)
45		return ret;
46
47	ddata->has_encoder = !!(val & STM32_LPTIM_ENC);
48
49	return 0;
50}
51
52static int stm32_lptimer_probe(struct platform_device *pdev)
53{
54	struct device *dev = &pdev->dev;
55	struct stm32_lptimer *ddata;
56	void __iomem *mmio;
57	int ret;
58
59	ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
60	if (!ddata)
61		return -ENOMEM;
62
63	mmio = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
64	if (IS_ERR(mmio))
65		return PTR_ERR(mmio);
66
67	ddata->regmap = devm_regmap_init_mmio_clk(dev, "mux", mmio,
68						  &stm32_lptimer_regmap_cfg);
69	if (IS_ERR(ddata->regmap))
70		return PTR_ERR(ddata->regmap);
71
72	ddata->clk = devm_clk_get(dev, NULL);
73	if (IS_ERR(ddata->clk))
74		return PTR_ERR(ddata->clk);
75
76	ret = stm32_lptimer_detect_encoder(ddata);
77	if (ret)
78		return ret;
79
80	platform_set_drvdata(pdev, ddata);
81
82	return devm_of_platform_populate(&pdev->dev);
83}
84
85static const struct of_device_id stm32_lptimer_of_match[] = {
86	{ .compatible = "st,stm32-lptimer", },
87	{},
88};
89MODULE_DEVICE_TABLE(of, stm32_lptimer_of_match);
90
91static struct platform_driver stm32_lptimer_driver = {
92	.probe = stm32_lptimer_probe,
93	.driver = {
94		.name = "stm32-lptimer",
95		.of_match_table = stm32_lptimer_of_match,
96	},
97};
98module_platform_driver(stm32_lptimer_driver);
99
100MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
101MODULE_DESCRIPTION("STMicroelectronics STM32 Low-Power Timer");
102MODULE_ALIAS("platform:stm32-lptimer");
103MODULE_LICENSE("GPL v2");
104