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
15 static 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 };
21
stm32_lptimer_detect_encoder(struct stm32_lptimer * ddata)22 static int stm32_lptimer_detect_encoder(struct stm32_lptimer *ddata)
23 {
24 u32 val;
25 int ret;
26
27 /*
28 * Quadrature encoder mode bit can only be written and read back when
29 * Low-Power Timer supports it.
30 */
31 ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,
32 STM32_LPTIM_ENC, STM32_LPTIM_ENC);
33 if (ret)
34 return ret;
35
36 ret = regmap_read(ddata->regmap, STM32_LPTIM_CFGR, &val);
37 if (ret)
38 return ret;
39
40 ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,
41 STM32_LPTIM_ENC, 0);
42 if (ret)
43 return ret;
44
45 ddata->has_encoder = !!(val & STM32_LPTIM_ENC);
46
47 return 0;
48 }
49
stm32_lptimer_probe(struct platform_device * pdev)50 static int stm32_lptimer_probe(struct platform_device *pdev)
51 {
52 struct device *dev = &pdev->dev;
53 struct stm32_lptimer *ddata;
54 struct resource *res;
55 void __iomem *mmio;
56 int ret;
57
58 ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
59 if (!ddata)
60 return -ENOMEM;
61
62 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
63 mmio = devm_ioremap_resource(dev, res);
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
85 static const struct of_device_id stm32_lptimer_of_match[] = {
86 { .compatible = "st,stm32-lptimer", },
87 {},
88 };
89 MODULE_DEVICE_TABLE(of, stm32_lptimer_of_match);
90
91 static 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 };
98 module_platform_driver(stm32_lptimer_driver);
99
100 MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
101 MODULE_DESCRIPTION("STMicroelectronics STM32 Low-Power Timer");
102 MODULE_ALIAS("platform:stm32-lptimer");
103 MODULE_LICENSE("GPL v2");
104