1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2014 Free Electrons
4  *
5  * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
6  *
7  * Allwinner A31 AR100 clock driver
8  */
9 
10 #include <linux/bitops.h>
11 #include <linux/clk-provider.h>
12 #include <linux/init.h>
13 #include <linux/of.h>
14 #include <linux/platform_device.h>
15 #include <linux/spinlock.h>
16 
17 #include "clk-factors.h"
18 
19 /*
20  * sun6i_get_ar100_factors - Calculates factors p, m for AR100
21  *
22  * AR100 rate is calculated as follows
23  * rate = (parent_rate >> p) / (m + 1);
24  */
25 static void sun6i_get_ar100_factors(struct factors_request *req)
26 {
27 	unsigned long div;
28 	int shift;
29 
30 	/* clock only divides */
31 	if (req->rate > req->parent_rate)
32 		req->rate = req->parent_rate;
33 
34 	div = DIV_ROUND_UP(req->parent_rate, req->rate);
35 
36 	if (div < 32)
37 		shift = 0;
38 	else if (div >> 1 < 32)
39 		shift = 1;
40 	else if (div >> 2 < 32)
41 		shift = 2;
42 	else
43 		shift = 3;
44 
45 	div >>= shift;
46 
47 	if (div > 32)
48 		div = 32;
49 
50 	req->rate = (req->parent_rate >> shift) / div;
51 	req->m = div - 1;
52 	req->p = shift;
53 }
54 
55 static const struct clk_factors_config sun6i_ar100_config = {
56 	.mwidth = 5,
57 	.mshift = 8,
58 	.pwidth = 2,
59 	.pshift = 4,
60 };
61 
62 static const struct factors_data sun6i_ar100_data = {
63 	.mux = 16,
64 	.muxmask = GENMASK(1, 0),
65 	.table = &sun6i_ar100_config,
66 	.getter = sun6i_get_ar100_factors,
67 };
68 
69 static DEFINE_SPINLOCK(sun6i_ar100_lock);
70 
71 static int sun6i_a31_ar100_clk_probe(struct platform_device *pdev)
72 {
73 	struct device_node *np = pdev->dev.of_node;
74 	void __iomem *reg;
75 	struct clk *clk;
76 
77 	reg = devm_platform_ioremap_resource(pdev, 0);
78 	if (IS_ERR(reg))
79 		return PTR_ERR(reg);
80 
81 	clk = sunxi_factors_register(np, &sun6i_ar100_data, &sun6i_ar100_lock,
82 				     reg);
83 	if (!clk)
84 		return -ENOMEM;
85 
86 	platform_set_drvdata(pdev, clk);
87 
88 	return 0;
89 }
90 
91 static const struct of_device_id sun6i_a31_ar100_clk_dt_ids[] = {
92 	{ .compatible = "allwinner,sun6i-a31-ar100-clk" },
93 	{ /* sentinel */ }
94 };
95 
96 static struct platform_driver sun6i_a31_ar100_clk_driver = {
97 	.driver = {
98 		.name = "sun6i-a31-ar100-clk",
99 		.of_match_table = sun6i_a31_ar100_clk_dt_ids,
100 		.suppress_bind_attrs = true,
101 	},
102 	.probe = sun6i_a31_ar100_clk_probe,
103 };
104 builtin_platform_driver(sun6i_a31_ar100_clk_driver);
105