linux/drivers/clk/tegra/clk-periph-gate.c
Peter De Schrijver 9619dba832 clk: tegra: Fix disable unused for clocks sharing enable bit
In case 2 clocks share an enable bit and one of them is enabled by a
driver and the other one is not, CCF will think it's enabled because it
will only look at the HW state. Therefore it will disable the clock and
thus also disable the other clock which was enabled. Solve this by
reading the initial state of the enable bit and incrementing the
refcount if it's set.

Signed-off-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
2017-03-20 14:13:52 +01:00

174 lines
4.7 KiB
C

/*
* 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-provider.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <soc/tegra/fuse.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;
const 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;
if (read_enb(gate) & periph_clk_to_bit(gate))
enable_refcnt[clk_num]++;
/* 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;
}