1 /*
2  * Copyright (C) 2014 Free Electrons
3  *
4  * License Terms: GNU General Public License v2
5  * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
6  *
7  * Allwinner A31 AR100 clock driver
8  *
9  */
10 
11 #include <linux/bitops.h>
12 #include <linux/clk-provider.h>
13 #include <linux/init.h>
14 #include <linux/of.h>
15 #include <linux/platform_device.h>
16 #include <linux/spinlock.h>
17 
18 #include "clk-factors.h"
19 
20 /**
21  * sun6i_get_ar100_factors - Calculates factors p, m for AR100
22  *
23  * AR100 rate is calculated as follows
24  * rate = (parent_rate >> p) / (m + 1);
25  */
26 static void sun6i_get_ar100_factors(struct factors_request *req)
27 {
28 	unsigned long div;
29 	int shift;
30 
31 	/* clock only divides */
32 	if (req->rate > req->parent_rate)
33 		req->rate = req->parent_rate;
34 
35 	div = DIV_ROUND_UP(req->parent_rate, req->rate);
36 
37 	if (div < 32)
38 		shift = 0;
39 	else if (div >> 1 < 32)
40 		shift = 1;
41 	else if (div >> 2 < 32)
42 		shift = 2;
43 	else
44 		shift = 3;
45 
46 	div >>= shift;
47 
48 	if (div > 32)
49 		div = 32;
50 
51 	req->rate = (req->parent_rate >> shift) / div;
52 	req->m = div - 1;
53 	req->p = shift;
54 }
55 
56 static const struct clk_factors_config sun6i_ar100_config = {
57 	.mwidth = 5,
58 	.mshift = 8,
59 	.pwidth = 2,
60 	.pshift = 4,
61 };
62 
63 static const struct factors_data sun6i_ar100_data = {
64 	.mux = 16,
65 	.muxmask = GENMASK(1, 0),
66 	.table = &sun6i_ar100_config,
67 	.getter = sun6i_get_ar100_factors,
68 };
69 
70 static DEFINE_SPINLOCK(sun6i_ar100_lock);
71 
72 static int sun6i_a31_ar100_clk_probe(struct platform_device *pdev)
73 {
74 	struct device_node *np = pdev->dev.of_node;
75 	struct resource *r;
76 	void __iomem *reg;
77 	struct clk *clk;
78 
79 	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
80 	reg = devm_ioremap_resource(&pdev->dev, r);
81 	if (IS_ERR(reg))
82 		return PTR_ERR(reg);
83 
84 	clk = sunxi_factors_register(np, &sun6i_ar100_data, &sun6i_ar100_lock,
85 				     reg);
86 	if (!clk)
87 		return -ENOMEM;
88 
89 	platform_set_drvdata(pdev, clk);
90 
91 	return 0;
92 }
93 
94 static const struct of_device_id sun6i_a31_ar100_clk_dt_ids[] = {
95 	{ .compatible = "allwinner,sun6i-a31-ar100-clk" },
96 	{ /* sentinel */ }
97 };
98 
99 static struct platform_driver sun6i_a31_ar100_clk_driver = {
100 	.driver = {
101 		.name = "sun6i-a31-ar100-clk",
102 		.of_match_table = sun6i_a31_ar100_clk_dt_ids,
103 		.suppress_bind_attrs = true,
104 	},
105 	.probe = sun6i_a31_ar100_clk_probe,
106 };
107 builtin_platform_driver(sun6i_a31_ar100_clk_driver);
108