clk/sunxi/clk-sun6i-ar100.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Copyright (C) 2014 Free Electrons
0004  *
0005  * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
0006  *
0007  * Allwinner A31 AR100 clock driver
0008  */
0009
0010 #include <linux/bitops.h>
0011 #include <linux/clk-provider.h>
0012 #include <linux/init.h>
0013 #include <linux/of.h>
0014 #include <linux/platform_device.h>
0015 #include <linux/spinlock.h>
0016
0017 #include "clk-factors.h"
0018
0019 /*
0020  * sun6i_get_ar100_factors - Calculates factors p, m for AR100
0021  *
0022  * AR100 rate is calculated as follows
0023  * rate = (parent_rate >> p) / (m + 1);
0024  */
0025 static void sun6i_get_ar100_factors(struct factors_request *req)
0026 {
0027     unsigned long div;
0028     int shift;
0029
0030     /* clock only divides */
0031     if (req->rate > req->parent_rate)
0032         req->rate = req->parent_rate;
0033
0034     div = DIV_ROUND_UP(req->parent_rate, req->rate);
0035
0036     if (div < 32)
0037         shift = 0;
0038     else if (div >> 1 < 32)
0039         shift = 1;
0040     else if (div >> 2 < 32)
0041         shift = 2;
0042     else
0043         shift = 3;
0044
0045     div >>= shift;
0046
0047     if (div > 32)
0048         div = 32;
0049
0050     req->rate = (req->parent_rate >> shift) / div;
0051     req->m = div - 1;
0052     req->p = shift;
0053 }
0054
0055 static const struct clk_factors_config sun6i_ar100_config = {
0056     .mwidth = 5,
0057     .mshift = 8,
0058     .pwidth = 2,
0059     .pshift = 4,
0060 };
0061
0062 static const struct factors_data sun6i_ar100_data = {
0063     .mux = 16,
0064     .muxmask = GENMASK(1, 0),
0065     .table = &sun6i_ar100_config,
0066     .getter = sun6i_get_ar100_factors,
0067 };
0068
0069 static DEFINE_SPINLOCK(sun6i_ar100_lock);
0070
0071 static int sun6i_a31_ar100_clk_probe(struct platform_device *pdev)
0072 {
0073     struct device_node *np = pdev->dev.of_node;
0074     void __iomem *reg;
0075     struct clk *clk;
0076
0077     reg = devm_platform_ioremap_resource(pdev, 0);
0078     if (IS_ERR(reg))
0079         return PTR_ERR(reg);
0080
0081     clk = sunxi_factors_register(np, &sun6i_ar100_data, &sun6i_ar100_lock,
0082                      reg);
0083     if (!clk)
0084         return -ENOMEM;
0085
0086     platform_set_drvdata(pdev, clk);
0087
0088     return 0;
0089 }
0090
0091 static const struct of_device_id sun6i_a31_ar100_clk_dt_ids[] = {
0092     { .compatible = "allwinner,sun6i-a31-ar100-clk" },
0093     { /* sentinel */ }
0094 };
0095
0096 static struct platform_driver sun6i_a31_ar100_clk_driver = {
0097     .driver = {
0098         .name = "sun6i-a31-ar100-clk",
0099         .of_match_table = sun6i_a31_ar100_clk_dt_ids,
0100         .suppress_bind_attrs = true,
0101     },
0102     .probe = sun6i_a31_ar100_clk_probe,
0103 };
0104 builtin_platform_driver(sun6i_a31_ar100_clk_driver);