diff options
Diffstat (limited to 'kernel/drivers/clk/sunxi/clk-a20-gmac.c')
| -rw-r--r-- | kernel/drivers/clk/sunxi/clk-a20-gmac.c | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/kernel/drivers/clk/sunxi/clk-a20-gmac.c b/kernel/drivers/clk/sunxi/clk-a20-gmac.c new file mode 100644 index 000000000..0dcf4f205 --- /dev/null +++ b/kernel/drivers/clk/sunxi/clk-a20-gmac.c @@ -0,0 +1,124 @@ +/* + * Copyright 2013 Emilio López + * Emilio López <emilio@elopez.com.ar> + * + * Copyright 2013 Chen-Yu Tsai + * Chen-Yu Tsai <wens@csie.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <linux/clk-provider.h> +#include <linux/clkdev.h> +#include <linux/of.h> +#include <linux/of_address.h> +#include <linux/slab.h> + +static DEFINE_SPINLOCK(gmac_lock); + +/** + * sun7i_a20_gmac_clk_setup - Setup function for A20/A31 GMAC clock module + * + * This clock looks something like this + * ________________________ + * MII TX clock from PHY >-----|___________ _________|----> to GMAC core + * GMAC Int. RGMII TX clk >----|___________\__/__gate---|----> to PHY + * Ext. 125MHz RGMII TX clk >--|__divider__/ | + * |________________________| + * + * The external 125 MHz reference is optional, i.e. GMAC can use its + * internal TX clock just fine. The A31 GMAC clock module does not have + * the divider controls for the external reference. + * + * To keep it simple, let the GMAC use either the MII TX clock for MII mode, + * and its internal TX clock for GMII and RGMII modes. The GMAC driver should + * select the appropriate source and gate/ungate the output to the PHY. + * + * Only the GMAC should use this clock. Altering the clock so that it doesn't + * match the GMAC's operation parameters will result in the GMAC not being + * able to send traffic out. The GMAC driver should set the clock rate and + * enable/disable this clock to configure the required state. The clock + * driver then responds by auto-reparenting the clock. + */ + +#define SUN7I_A20_GMAC_GPIT 2 +#define SUN7I_A20_GMAC_MASK 0x3 +#define SUN7I_A20_GMAC_PARENTS 2 + +static u32 sun7i_a20_gmac_mux_table[SUN7I_A20_GMAC_PARENTS] = { + 0x00, /* Select mii_phy_tx_clk */ + 0x02, /* Select gmac_int_tx_clk */ +}; + +static void __init sun7i_a20_gmac_clk_setup(struct device_node *node) +{ + struct clk *clk; + struct clk_mux *mux; + struct clk_gate *gate; + const char *clk_name = node->name; + const char *parents[SUN7I_A20_GMAC_PARENTS]; + void __iomem *reg; + + if (of_property_read_string(node, "clock-output-names", &clk_name)) + return; + + /* allocate mux and gate clock structs */ + mux = kzalloc(sizeof(struct clk_mux), GFP_KERNEL); + if (!mux) + return; + + gate = kzalloc(sizeof(struct clk_gate), GFP_KERNEL); + if (!gate) + goto free_mux; + + /* gmac clock requires exactly 2 parents */ + parents[0] = of_clk_get_parent_name(node, 0); + parents[1] = of_clk_get_parent_name(node, 1); + if (!parents[0] || !parents[1]) + goto free_gate; + + reg = of_iomap(node, 0); + if (!reg) + goto free_gate; + + /* set up gate and fixed rate properties */ + gate->reg = reg; + gate->bit_idx = SUN7I_A20_GMAC_GPIT; + gate->lock = &gmac_lock; + mux->reg = reg; + mux->mask = SUN7I_A20_GMAC_MASK; + mux->table = sun7i_a20_gmac_mux_table; + mux->lock = &gmac_lock; + + clk = clk_register_composite(NULL, clk_name, + parents, SUN7I_A20_GMAC_PARENTS, + &mux->hw, &clk_mux_ops, + NULL, NULL, + &gate->hw, &clk_gate_ops, + 0); + + if (IS_ERR(clk)) + goto iounmap_reg; + + of_clk_add_provider(node, of_clk_src_simple_get, clk); + clk_register_clkdev(clk, clk_name, NULL); + + return; + +iounmap_reg: + iounmap(reg); +free_gate: + kfree(gate); +free_mux: + kfree(mux); +} +CLK_OF_DECLARE(sun7i_a20_gmac, "allwinner,sun7i-a20-gmac-clk", + sun7i_a20_gmac_clk_setup); |