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linux-next/arch/powerpc/kernel/udbg_16550.c
Anton Blanchard cd32e2dcc9 powerpc: Fix bad NULL pointer check in udbg_uart_getc_poll() 
We have some code in udbg_uart_getc_poll() that tries to protect
against a NULL udbg_uart_in, but gets it all wrong.

Found with the LLVM static analyzer (scan-build).

Fixes: 309257484c ("powerpc: Cleanup udbg_16550 and add support for LPC PIO-only UARTs")
Signed-off-by: Anton Blanchard <anton@samba.org>
[mpe: Add some newlines for readability while we're here]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2014-11-12 13:47:20 +11:00

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6.4 KiB
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/*
* udbg for NS16550 compatible serial ports
*
* Copyright (C) 2001-2005 PPC 64 Team, IBM Corp
*
* 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.
*/
#include <linux/types.h>
#include <asm/udbg.h>
#include <asm/io.h>
#include <asm/reg_a2.h>
extern u8 real_readb(volatile u8 __iomem *addr);
extern void real_writeb(u8 data, volatile u8 __iomem *addr);
extern u8 real_205_readb(volatile u8 __iomem *addr);
extern void real_205_writeb(u8 data, volatile u8 __iomem *addr);
#define UART_RBR 0
#define UART_IER 1
#define UART_FCR 2
#define UART_LCR 3
#define UART_MCR 4
#define UART_LSR 5
#define UART_MSR 6
#define UART_SCR 7
#define UART_THR UART_RBR
#define UART_IIR UART_FCR
#define UART_DLL UART_RBR
#define UART_DLM UART_IER
#define UART_DLAB UART_LCR
#define LSR_DR 0x01 /* Data ready */
#define LSR_OE 0x02 /* Overrun */
#define LSR_PE 0x04 /* Parity error */
#define LSR_FE 0x08 /* Framing error */
#define LSR_BI 0x10 /* Break */
#define LSR_THRE 0x20 /* Xmit holding register empty */
#define LSR_TEMT 0x40 /* Xmitter empty */
#define LSR_ERR 0x80 /* Error */
#define LCR_DLAB 0x80
static u8 (*udbg_uart_in)(unsigned int reg);
static void (*udbg_uart_out)(unsigned int reg, u8 data);
static void udbg_uart_flush(void)
{
if (!udbg_uart_in)
return;
/* wait for idle */
while ((udbg_uart_in(UART_LSR) & LSR_THRE) == 0)
cpu_relax();
}
static void udbg_uart_putc(char c)
{
if (!udbg_uart_out)
return;
if (c == '\n')
udbg_uart_putc('\r');
udbg_uart_flush();
udbg_uart_out(UART_THR, c);
}
static int udbg_uart_getc_poll(void)
{
if (!udbg_uart_in)
return -1;
if (!(udbg_uart_in(UART_LSR) & LSR_DR))
return udbg_uart_in(UART_RBR);
return -1;
}
static int udbg_uart_getc(void)
{
if (!udbg_uart_in)
return -1;
/* wait for char */
while (!(udbg_uart_in(UART_LSR) & LSR_DR))
cpu_relax();
return udbg_uart_in(UART_RBR);
}
static void udbg_use_uart(void)
{
udbg_putc = udbg_uart_putc;
udbg_flush = udbg_uart_flush;
udbg_getc = udbg_uart_getc;
udbg_getc_poll = udbg_uart_getc_poll;
}
void udbg_uart_setup(unsigned int speed, unsigned int clock)
{
unsigned int dll, base_bauds;
if (!udbg_uart_out)
return;
if (clock == 0)
clock = 1843200;
if (speed == 0)
speed = 9600;
base_bauds = clock / 16;
dll = base_bauds / speed;
udbg_uart_out(UART_LCR, 0x00);
udbg_uart_out(UART_IER, 0xff);
udbg_uart_out(UART_IER, 0x00);
udbg_uart_out(UART_LCR, LCR_DLAB);
udbg_uart_out(UART_DLL, dll & 0xff);
udbg_uart_out(UART_DLM, dll >> 8);
/* 8 data, 1 stop, no parity */
udbg_uart_out(UART_LCR, 0x3);
/* RTS/DTR */
udbg_uart_out(UART_MCR, 0x3);
/* Clear & enable FIFOs */
udbg_uart_out(UART_FCR, 0x7);
}
unsigned int udbg_probe_uart_speed(unsigned int clock)
{
unsigned int dll, dlm, divisor, prescaler, speed;
u8 old_lcr;
old_lcr = udbg_uart_in(UART_LCR);
/* select divisor latch registers. */
udbg_uart_out(UART_LCR, old_lcr | LCR_DLAB);
/* now, read the divisor */
dll = udbg_uart_in(UART_DLL);
dlm = udbg_uart_in(UART_DLM);
divisor = dlm << 8 | dll;
/* check prescaling */
if (udbg_uart_in(UART_MCR) & 0x80)
prescaler = 4;
else
prescaler = 1;
/* restore the LCR */
udbg_uart_out(UART_LCR, old_lcr);
/* calculate speed */
speed = (clock / prescaler) / (divisor * 16);
/* sanity check */
if (speed > (clock / 16))
speed = 9600;
return speed;
}
static union {
unsigned char __iomem *mmio_base;
unsigned long pio_base;
} udbg_uart;
static unsigned int udbg_uart_stride = 1;
static u8 udbg_uart_in_pio(unsigned int reg)
{
return inb(udbg_uart.pio_base + (reg * udbg_uart_stride));
}
static void udbg_uart_out_pio(unsigned int reg, u8 data)
{
outb(data, udbg_uart.pio_base + (reg * udbg_uart_stride));
}
void udbg_uart_init_pio(unsigned long port, unsigned int stride)
{
if (!port)
return;
udbg_uart.pio_base = port;
udbg_uart_stride = stride;
udbg_uart_in = udbg_uart_in_pio;
udbg_uart_out = udbg_uart_out_pio;
udbg_use_uart();
}
static u8 udbg_uart_in_mmio(unsigned int reg)
{
return in_8(udbg_uart.mmio_base + (reg * udbg_uart_stride));
}
static void udbg_uart_out_mmio(unsigned int reg, u8 data)
{
out_8(udbg_uart.mmio_base + (reg * udbg_uart_stride), data);
}
void udbg_uart_init_mmio(void __iomem *addr, unsigned int stride)
{
if (!addr)
return;
udbg_uart.mmio_base = addr;
udbg_uart_stride = stride;
udbg_uart_in = udbg_uart_in_mmio;
udbg_uart_out = udbg_uart_out_mmio;
udbg_use_uart();
}
#ifdef CONFIG_PPC_MAPLE
#define UDBG_UART_MAPLE_ADDR ((void __iomem *)0xf40003f8)
static u8 udbg_uart_in_maple(unsigned int reg)
{
return real_readb(UDBG_UART_MAPLE_ADDR + reg);
}
static void udbg_uart_out_maple(unsigned int reg, u8 val)
{
real_writeb(val, UDBG_UART_MAPLE_ADDR + reg);
}
void __init udbg_init_maple_realmode(void)
{
udbg_uart_in = udbg_uart_in_maple;
udbg_uart_out = udbg_uart_out_maple;
udbg_use_uart();
}
#endif /* CONFIG_PPC_MAPLE */
#ifdef CONFIG_PPC_PASEMI
#define UDBG_UART_PAS_ADDR ((void __iomem *)0xfcff03f8UL)
static u8 udbg_uart_in_pas(unsigned int reg)
{
return real_205_readb(UDBG_UART_PAS_ADDR + reg);
}
static void udbg_uart_out_pas(unsigned int reg, u8 val)
{
real_205_writeb(val, UDBG_UART_PAS_ADDR + reg);
}
void __init udbg_init_pas_realmode(void)
{
udbg_uart_in = udbg_uart_in_pas;
udbg_uart_out = udbg_uart_out_pas;
udbg_use_uart();
}
#endif /* CONFIG_PPC_PASEMI */
#ifdef CONFIG_PPC_EARLY_DEBUG_44x
#include <platforms/44x/44x.h>
static u8 udbg_uart_in_44x_as1(unsigned int reg)
{
return as1_readb((void __iomem *)PPC44x_EARLY_DEBUG_VIRTADDR + reg);
}
static void udbg_uart_out_44x_as1(unsigned int reg, u8 val)
{
as1_writeb(val, (void __iomem *)PPC44x_EARLY_DEBUG_VIRTADDR + reg);
}
void __init udbg_init_44x_as1(void)
{
udbg_uart_in = udbg_uart_in_44x_as1;
udbg_uart_out = udbg_uart_out_44x_as1;
udbg_use_uart();
}
#endif /* CONFIG_PPC_EARLY_DEBUG_44x */
#ifdef CONFIG_PPC_EARLY_DEBUG_40x
static u8 udbg_uart_in_40x(unsigned int reg)
{
return real_readb((void __iomem *)CONFIG_PPC_EARLY_DEBUG_40x_PHYSADDR
+ reg);
}
static void udbg_uart_out_40x(unsigned int reg, u8 val)
{
real_writeb(val, (void __iomem *)CONFIG_PPC_EARLY_DEBUG_40x_PHYSADDR
+ reg);
}
void __init udbg_init_40x_realmode(void)
{
udbg_uart_in = udbg_uart_in_40x;
udbg_uart_out = udbg_uart_out_40x;
udbg_use_uart();
}
#endif /* CONFIG_PPC_EARLY_DEBUG_40x */
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