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gpio: mpc8xxx: Do not reverse bits using bgpio 

The MPC8xxx driver is always instantiating its generic GPIO functions
with the flag BGPIOF_BIG_ENDIAN. This means "big-endian bit order"
and means the bits representing the GPIO lines in the registers are
reversed around 31 bits so line 0 is at bit 31 and so forth down to
line 31 in bit 0.

Instead of looping into the generic MMIO gpio to do the simple
calculation of a bitmask, through a vtable call with two parameters
likely using stack frames etc (unless the compiler optimize it)
and obscuring the view for the programmer, let's just open-code
what the call does. This likely executes faster, saves space and
makes the code easier to read.

Cc: Liu Gang <Gang.Liu@nxp.com>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Linus Walleij 2017-10-20 16:08:12 +02:00
parent d74423687f
commit b3222f7147
1 changed files with 17 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
drivers/gpio/gpio-mpc8xxx.c
View File

@ -21,6 +21,7 @@
#include <linux/slab.h>
#include <linux/irq.h>
#include <linux/gpio/driver.h>
#include <linux/bitops.h>
#define MPC8XXX_GPIO_PINS 32
@ -44,6 +45,16 @@ struct mpc8xxx_gpio_chip {
unsigned int irqn;
};
/*
* This hardware has a big endian bit assignment such that GPIO line 0 is
* connected to bit 31, line 1 to bit 30 ... line 31 to bit 0.
* This inline helper give the right bitmask for a certain line.
*/
static inline u32 mpc_pin2mask(unsigned int offset)
{
return BIT(31 - offset);
}
/* Workaround GPIO 1 errata on MPC8572/MPC8536. The status of GPIOs
* defined as output cannot be determined by reading GPDAT register,
* so we use shadow data register instead. The status of input pins
@ -59,7 +70,7 @@ static int mpc8572_gpio_get(struct gpio_chip *gc, unsigned int gpio)
val = gc->read_reg(mpc8xxx_gc->regs + GPIO_DAT) & ~out_mask;
out_shadow = gc->bgpio_data & out_mask;
return !!((val | out_shadow) & gc->pin2mask(gc, gpio));
return !!((val | out_shadow) & mpc_pin2mask(gpio));
}
static int mpc5121_gpio_dir_out(struct gpio_chip *gc,
@ -120,7 +131,7 @@ static void mpc8xxx_irq_unmask(struct irq_data *d)
gc->write_reg(mpc8xxx_gc->regs + GPIO_IMR,
gc->read_reg(mpc8xxx_gc->regs + GPIO_IMR)
| gc->pin2mask(gc, irqd_to_hwirq(d)));
| mpc_pin2mask(irqd_to_hwirq(d)));
raw_spin_unlock_irqrestore(&mpc8xxx_gc->lock, flags);
}
@ -135,7 +146,7 @@ static void mpc8xxx_irq_mask(struct irq_data *d)
gc->write_reg(mpc8xxx_gc->regs + GPIO_IMR,
gc->read_reg(mpc8xxx_gc->regs + GPIO_IMR)
& ~(gc->pin2mask(gc, irqd_to_hwirq(d))));
& ~mpc_pin2mask(irqd_to_hwirq(d)));
raw_spin_unlock_irqrestore(&mpc8xxx_gc->lock, flags);
}
@ -146,7 +157,7 @@ static void mpc8xxx_irq_ack(struct irq_data *d)
struct gpio_chip *gc = &mpc8xxx_gc->gc;
gc->write_reg(mpc8xxx_gc->regs + GPIO_IER,
gc->pin2mask(gc, irqd_to_hwirq(d)));
mpc_pin2mask(irqd_to_hwirq(d)));
}
static int mpc8xxx_irq_set_type(struct irq_data *d, unsigned int flow_type)
@ -160,7 +171,7 @@ static int mpc8xxx_irq_set_type(struct irq_data *d, unsigned int flow_type)
raw_spin_lock_irqsave(&mpc8xxx_gc->lock, flags);
gc->write_reg(mpc8xxx_gc->regs + GPIO_ICR,
gc->read_reg(mpc8xxx_gc->regs + GPIO_ICR)
| gc->pin2mask(gc, irqd_to_hwirq(d)));
| mpc_pin2mask(irqd_to_hwirq(d)));
raw_spin_unlock_irqrestore(&mpc8xxx_gc->lock, flags);
break;
@ -168,7 +179,7 @@ static int mpc8xxx_irq_set_type(struct irq_data *d, unsigned int flow_type)
raw_spin_lock_irqsave(&mpc8xxx_gc->lock, flags);
gc->write_reg(mpc8xxx_gc->regs + GPIO_ICR,
gc->read_reg(mpc8xxx_gc->regs + GPIO_ICR)
& ~(gc->pin2mask(gc, irqd_to_hwirq(d))));
& ~mpc_pin2mask(irqd_to_hwirq(d)));
raw_spin_unlock_irqrestore(&mpc8xxx_gc->lock, flags);
break;