tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * STM32 Low-Power Timer parent driver.
3 *
4 * Copyright (C) STMicroelectronics 2017
5 *
6 * Author: Fabrice Gasnier <fabrice.gasnier@st.com>
7 *
8 * Inspired by Benjamin Gaignard's stm32-timers driver
9 *
10 * License terms: GNU General Public License (GPL), version 2
11 */
12
13#include <linux/mfd/stm32-lptimer.h>
14#include <linux/module.h>
15#include <linux/of_platform.h>
16
17#define STM32_LPTIM_MAX_REGISTER 0x3fc
18
19static const struct regmap_config stm32_lptimer_regmap_cfg = {
20 .reg_bits = 32,
21 .val_bits = 32,
22 .reg_stride = sizeof(u32),
23 .max_register = STM32_LPTIM_MAX_REGISTER,
24};
25
26static int stm32_lptimer_detect_encoder(struct stm32_lptimer *ddata)
27{
28 u32 val;
29 int ret;
30
31 /*
32 * Quadrature encoder mode bit can only be written and read back when
33 * Low-Power Timer supports it.
34 */
35 ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,
36 STM32_LPTIM_ENC, STM32_LPTIM_ENC);
37 if (ret)
38 return ret;
39
40 ret = regmap_read(ddata->regmap, STM32_LPTIM_CFGR, &val);
41 if (ret)
42 return ret;
43
44 ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,
45 STM32_LPTIM_ENC, 0);
46 if (ret)
47 return ret;
48
49 ddata->has_encoder = !!(val & STM32_LPTIM_ENC);
50
51 return 0;
52}
53
54static int stm32_lptimer_probe(struct platform_device *pdev)
55{
56 struct device *dev = &pdev->dev;
57 struct stm32_lptimer *ddata;
58 struct resource *res;
59 void __iomem *mmio;
60 int ret;
61
62 ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
63 if (!ddata)
64 return -ENOMEM;
65
66 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
67 mmio = devm_ioremap_resource(dev, res);
68 if (IS_ERR(mmio))
69 return PTR_ERR(mmio);
70
71 ddata->regmap = devm_regmap_init_mmio_clk(dev, "mux", mmio,
72 &stm32_lptimer_regmap_cfg);
73 if (IS_ERR(ddata->regmap))
74 return PTR_ERR(ddata->regmap);
75
76 ddata->clk = devm_clk_get(dev, NULL);
77 if (IS_ERR(ddata->clk))
78 return PTR_ERR(ddata->clk);
79
80 ret = stm32_lptimer_detect_encoder(ddata);
81 if (ret)
82 return ret;
83
84 platform_set_drvdata(pdev, ddata);
85
86 return devm_of_platform_populate(&pdev->dev);
87}
88
89static const struct of_device_id stm32_lptimer_of_match[] = {
90 { .compatible = "st,stm32-lptimer", },
91 {},
92};
93MODULE_DEVICE_TABLE(of, stm32_lptimer_of_match);
94
95static struct platform_driver stm32_lptimer_driver = {
96 .probe = stm32_lptimer_probe,
97 .driver = {
98 .name = "stm32-lptimer",
99 .of_match_table = stm32_lptimer_of_match,
100 },
101};
102module_platform_driver(stm32_lptimer_driver);
103
104MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
105MODULE_DESCRIPTION("STMicroelectronics STM32 Low-Power Timer");
106MODULE_ALIAS("platform:stm32-lptimer");
107MODULE_LICENSE("GPL v2");