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
13#define STM32_LPTIM_MAX_REGISTER	0x3fc
14
15static const struct regmap_config stm32_lptimer_regmap_cfg = {
16	.reg_bits = 32,
17	.val_bits = 32,
18	.reg_stride = sizeof(u32),
19	.max_register = STM32_LPTIM_MAX_REGISTER,
20	.fast_io = true,
21};
22
23static int stm32_lptimer_detect_encoder(struct stm32_lptimer *ddata)
24{
25	u32 val;
26	int ret;
27
28	/*
29	 * Quadrature encoder mode bit can only be written and read back when
30	 * Low-Power Timer supports it.
31	 */
32	ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,
33				 STM32_LPTIM_ENC, STM32_LPTIM_ENC);
34	if (ret)
35		return ret;
36
37	ret = regmap_read(ddata->regmap, STM32_LPTIM_CFGR, &val);
38	if (ret)
39		return ret;
40
41	ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,
42				 STM32_LPTIM_ENC, 0);
43	if (ret)
44		return ret;
45
46	ddata->has_encoder = !!(val & STM32_LPTIM_ENC);
47
48	return 0;
49}
50
51static int stm32_lptimer_probe(struct platform_device *pdev)
52{
53	struct device *dev = &pdev->dev;
54	struct stm32_lptimer *ddata;
55	struct resource *res;
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	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
64	mmio = devm_ioremap_resource(dev, res);
65	if (IS_ERR(mmio))
66		return PTR_ERR(mmio);
67
68	ddata->regmap = devm_regmap_init_mmio_clk(dev, "mux", mmio,
69						  &stm32_lptimer_regmap_cfg);
70	if (IS_ERR(ddata->regmap))
71		return PTR_ERR(ddata->regmap);
72
73	ddata->clk = devm_clk_get(dev, NULL);
74	if (IS_ERR(ddata->clk))
75		return PTR_ERR(ddata->clk);
76
77	ret = stm32_lptimer_detect_encoder(ddata);
78	if (ret)
79		return ret;
80
81	platform_set_drvdata(pdev, ddata);
82
83	return devm_of_platform_populate(&pdev->dev);
84}
85
86static const struct of_device_id stm32_lptimer_of_match[] = {
87	{ .compatible = "st,stm32-lptimer", },
88	{},
89};
90MODULE_DEVICE_TABLE(of, stm32_lptimer_of_match);
91
92static struct platform_driver stm32_lptimer_driver = {
93	.probe = stm32_lptimer_probe,
94	.driver = {
95		.name = "stm32-lptimer",
96		.of_match_table = stm32_lptimer_of_match,
97	},
98};
99module_platform_driver(stm32_lptimer_driver);
100
101MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
102MODULE_DESCRIPTION("STMicroelectronics STM32 Low-Power Timer");
103MODULE_ALIAS("platform:stm32-lptimer");
104MODULE_LICENSE("GPL v2");
105