linux/drivers/clk/sunxi/clk-a20-gmac.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * Copyright 2013 Emilio L\xC3\xB3pez
   4 * Emilio L\xC3\xB3pez <emilio@elopez.com.ar>
   5 *
   6 * Copyright 2013 Chen-Yu Tsai
   7 * Chen-Yu Tsai <wens@csie.org>
   8 */
   9
  10#include <linux/clk-provider.h>
  11#include <linux/io.h>
  12#include <linux/of.h>
  13#include <linux/of_address.h>
  14#include <linux/slab.h>
  15
  16static DEFINE_SPINLOCK(gmac_lock);
  17
  18/**
  19 * sun7i_a20_gmac_clk_setup - Setup function for A20/A31 GMAC clock module
  20 *
  21 * This clock looks something like this
  22 *                               ________________________
  23 *  MII TX clock from PHY >-----|___________    _________|----> to GMAC core
  24 *  GMAC Int. RGMII TX clk >----|___________\__/__gate---|----> to PHY
  25 *  Ext. 125MHz RGMII TX clk >--|__divider__/            |
  26 *                              |________________________|
  27 *
  28 * The external 125 MHz reference is optional, i.e. GMAC can use its
  29 * internal TX clock just fine. The A31 GMAC clock module does not have
  30 * the divider controls for the external reference.
  31 *
  32 * To keep it simple, let the GMAC use either the MII TX clock for MII mode,
  33 * and its internal TX clock for GMII and RGMII modes. The GMAC driver should
  34 * select the appropriate source and gate/ungate the output to the PHY.
  35 *
  36 * Only the GMAC should use this clock. Altering the clock so that it doesn't
  37 * match the GMAC's operation parameters will result in the GMAC not being
  38 * able to send traffic out. The GMAC driver should set the clock rate and
  39 * enable/disable this clock to configure the required state. The clock
  40 * driver then responds by auto-reparenting the clock.
  41 */
  42
  43#define SUN7I_A20_GMAC_GPIT     2
  44#define SUN7I_A20_GMAC_MASK     0x3
  45#define SUN7I_A20_GMAC_PARENTS  2
  46
  47static u32 sun7i_a20_gmac_mux_table[SUN7I_A20_GMAC_PARENTS] = {
  48        0x00, /* Select mii_phy_tx_clk */
  49        0x02, /* Select gmac_int_tx_clk */
  50};
  51
  52static void __init sun7i_a20_gmac_clk_setup(struct device_node *node)
  53{
  54        struct clk *clk;
  55        struct clk_mux *mux;
  56        struct clk_gate *gate;
  57        const char *clk_name = node->name;
  58        const char *parents[SUN7I_A20_GMAC_PARENTS];
  59        void __iomem *reg;
  60
  61        if (of_property_read_string(node, "clock-output-names", &clk_name))
  62                return;
  63
  64        /* allocate mux and gate clock structs */
  65        mux = kzalloc(sizeof(struct clk_mux), GFP_KERNEL);
  66        if (!mux)
  67                return;
  68
  69        gate = kzalloc(sizeof(struct clk_gate), GFP_KERNEL);
  70        if (!gate)
  71                goto free_mux;
  72
  73        /* gmac clock requires exactly 2 parents */
  74        if (of_clk_parent_fill(node, parents, 2) != 2)
  75                goto free_gate;
  76
  77        reg = of_iomap(node, 0);
  78        if (!reg)
  79                goto free_gate;
  80
  81        /* set up gate and fixed rate properties */
  82        gate->reg = reg;
  83        gate->bit_idx = SUN7I_A20_GMAC_GPIT;
  84        gate->lock = &gmac_lock;
  85        mux->reg = reg;
  86        mux->mask = SUN7I_A20_GMAC_MASK;
  87        mux->table = sun7i_a20_gmac_mux_table;
  88        mux->lock = &gmac_lock;
  89
  90        clk = clk_register_composite(NULL, clk_name,
  91                        parents, SUN7I_A20_GMAC_PARENTS,
  92                        &mux->hw, &clk_mux_ops,
  93                        NULL, NULL,
  94                        &gate->hw, &clk_gate_ops,
  95                        0);
  96
  97        if (IS_ERR(clk))
  98                goto iounmap_reg;
  99
 100        of_clk_add_provider(node, of_clk_src_simple_get, clk);
 101
 102        return;
 103
 104iounmap_reg:
 105        iounmap(reg);
 106free_gate:
 107        kfree(gate);
 108free_mux:
 109        kfree(mux);
 110}
 111CLK_OF_DECLARE(sun7i_a20_gmac, "allwinner,sun7i-a20-gmac-clk",
 112                sun7i_a20_gmac_clk_setup);
 113