clk-periph-gate.c
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/*
* Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/tegra-soc.h>
#include "clk.h"
static DEFINE_SPINLOCK(periph_ref_lock);
/* Macros to assist peripheral gate clock */
#define read_enb(gate) \
readl_relaxed(gate->clk_base + (gate->regs->enb_reg))
#define write_enb_set(val, gate) \
writel_relaxed(val, gate->clk_base + (gate->regs->enb_set_reg))
#define write_enb_clr(val, gate) \
writel_relaxed(val, gate->clk_base + (gate->regs->enb_clr_reg))
#define read_rst(gate) \
readl_relaxed(gate->clk_base + (gate->regs->rst_reg))
#define write_rst_clr(val, gate) \
writel_relaxed(val, gate->clk_base + (gate->regs->rst_clr_reg))
#define periph_clk_to_bit(gate) (1 << (gate->clk_num % 32))
#define LVL2_CLK_GATE_OVRE 0x554
/* Peripheral gate clock ops */
static int clk_periph_is_enabled(struct clk_hw *hw)
{
struct tegra_clk_periph_gate *gate = to_clk_periph_gate(hw);
int state = 1;
if (!(read_enb(gate) & periph_clk_to_bit(gate)))
state = 0;
if (!(gate->flags & TEGRA_PERIPH_NO_RESET))
if (read_rst(gate) & periph_clk_to_bit(gate))
state = 0;
return state;
}
static int clk_periph_enable(struct clk_hw *hw)
{
struct tegra_clk_periph_gate *gate = to_clk_periph_gate(hw);
unsigned long flags = 0;
spin_lock_irqsave(&periph_ref_lock, flags);
gate->enable_refcnt[gate->clk_num]++;
if (gate->enable_refcnt[gate->clk_num] > 1) {
spin_unlock_irqrestore(&periph_ref_lock, flags);
return 0;
}
write_enb_set(periph_clk_to_bit(gate), gate);
udelay(2);
if (!(gate->flags & TEGRA_PERIPH_NO_RESET) &&
!(gate->flags & TEGRA_PERIPH_MANUAL_RESET)) {
if (read_rst(gate) & periph_clk_to_bit(gate)) {
udelay(5); /* reset propogation delay */
write_rst_clr(periph_clk_to_bit(gate), gate);
}
}
if (gate->flags & TEGRA_PERIPH_WAR_1005168) {
writel_relaxed(0, gate->clk_base + LVL2_CLK_GATE_OVRE);
writel_relaxed(BIT(22), gate->clk_base + LVL2_CLK_GATE_OVRE);
udelay(1);
writel_relaxed(0, gate->clk_base + LVL2_CLK_GATE_OVRE);
}
spin_unlock_irqrestore(&periph_ref_lock, flags);
return 0;
}
static void clk_periph_disable(struct clk_hw *hw)
{
struct tegra_clk_periph_gate *gate = to_clk_periph_gate(hw);
unsigned long flags = 0;
spin_lock_irqsave(&periph_ref_lock, flags);
gate->enable_refcnt[gate->clk_num]--;
if (gate->enable_refcnt[gate->clk_num] > 0) {
spin_unlock_irqrestore(&periph_ref_lock, flags);
return;
}
/*
* If peripheral is in the APB bus then read the APB bus to
* flush the write operation in apb bus. This will avoid the
* peripheral access after disabling clock
*/
if (gate->flags & TEGRA_PERIPH_ON_APB)
tegra_read_chipid();
write_enb_clr(periph_clk_to_bit(gate), gate);
spin_unlock_irqrestore(&periph_ref_lock, flags);
}
const struct clk_ops tegra_clk_periph_gate_ops = {
.is_enabled = clk_periph_is_enabled,
.enable = clk_periph_enable,
.disable = clk_periph_disable,
};
struct clk *tegra_clk_register_periph_gate(const char *name,
const char *parent_name, u8 gate_flags, void __iomem *clk_base,
unsigned long flags, int clk_num, int *enable_refcnt)
{
struct tegra_clk_periph_gate *gate;
struct clk *clk;
struct clk_init_data init;
struct tegra_clk_periph_regs *pregs;
pregs = get_reg_bank(clk_num);
if (!pregs)
return ERR_PTR(-EINVAL);
gate = kzalloc(sizeof(*gate), GFP_KERNEL);
if (!gate) {
pr_err("%s: could not allocate periph gate clk\n", __func__);
return ERR_PTR(-ENOMEM);
}
init.name = name;
init.flags = flags;
init.parent_names = parent_name ? &parent_name : NULL;
init.num_parents = parent_name ? 1 : 0;
init.ops = &tegra_clk_periph_gate_ops;
gate->magic = TEGRA_CLK_PERIPH_GATE_MAGIC;
gate->clk_base = clk_base;
gate->clk_num = clk_num;
gate->flags = gate_flags;
gate->enable_refcnt = enable_refcnt;
gate->regs = pregs;
/* Data in .init is copied by clk_register(), so stack variable OK */
gate->hw.init = &init;
clk = clk_register(NULL, &gate->hw);
if (IS_ERR(clk))
kfree(gate);
return clk;
}