From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-Id: <20120309190202.844543140@linuxfoundation.org> Date: Fri, 09 Mar 2012 11:02:08 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Roland Stigge Subject: [ 06/95] ARM: LPC32xx: serial.c: HW bug workaround In-Reply-To: <20120309194424.GA2134@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Roland Stigge commit 2707208ee8a80dbbd5426f5aa1a934f766825bb5 upstream. This patch fixes a HW bug by flushing RX FIFOs of the UARTs on init. It was ported from NXP's git.lpclinux.com tree. Signed-off-by: Roland Stigge Signed-off-by: Greg Kroah-Hartman --- arch/arm/mach-lpc32xx/serial.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) --- a/arch/arm/mach-lpc32xx/serial.c +++ b/arch/arm/mach-lpc32xx/serial.c @@ -88,6 +88,7 @@ struct uartinit { char *uart_ck_name; u32 ck_mode_mask; void __iomem *pdiv_clk_reg; + resource_size_t mapbase; }; static struct uartinit uartinit_data[] __initdata = { @@ -97,6 +98,7 @@ static struct uartinit uartinit_data[] _ .ck_mode_mask = LPC32XX_UART_CLKMODE_LOAD(LPC32XX_UART_CLKMODE_ON, 5), .pdiv_clk_reg = LPC32XX_CLKPWR_UART5_CLK_CTRL, + .mapbase = LPC32XX_UART5_BASE, }, #endif #ifdef CONFIG_ARCH_LPC32XX_UART3_SELECT @@ -105,6 +107,7 @@ static struct uartinit uartinit_data[] _ .ck_mode_mask = LPC32XX_UART_CLKMODE_LOAD(LPC32XX_UART_CLKMODE_ON, 3), .pdiv_clk_reg = LPC32XX_CLKPWR_UART3_CLK_CTRL, + .mapbase = LPC32XX_UART3_BASE, }, #endif #ifdef CONFIG_ARCH_LPC32XX_UART4_SELECT @@ -113,6 +116,7 @@ static struct uartinit uartinit_data[] _ .ck_mode_mask = LPC32XX_UART_CLKMODE_LOAD(LPC32XX_UART_CLKMODE_ON, 4), .pdiv_clk_reg = LPC32XX_CLKPWR_UART4_CLK_CTRL, + .mapbase = LPC32XX_UART4_BASE, }, #endif #ifdef CONFIG_ARCH_LPC32XX_UART6_SELECT @@ -121,6 +125,7 @@ static struct uartinit uartinit_data[] _ .ck_mode_mask = LPC32XX_UART_CLKMODE_LOAD(LPC32XX_UART_CLKMODE_ON, 6), .pdiv_clk_reg = LPC32XX_CLKPWR_UART6_CLK_CTRL, + .mapbase = LPC32XX_UART6_BASE, }, #endif }; @@ -165,6 +170,19 @@ void __init lpc32xx_serial_init(void) /* pre-UART clock divider set to 1 */ __raw_writel(0x0101, uartinit_data[i].pdiv_clk_reg); + + /* + * Force a flush of the RX FIFOs to work around a + * HW bug + */ + puart = uartinit_data[i].mapbase; + __raw_writel(0xC1, LPC32XX_UART_IIR_FCR(puart)); + __raw_writel(0x00, LPC32XX_UART_DLL_FIFO(puart)); + j = LPC32XX_SUART_FIFO_SIZE; + while (j--) + tmp = __raw_readl( + LPC32XX_UART_DLL_FIFO(puart)); + __raw_writel(0, LPC32XX_UART_IIR_FCR(puart)); } /* This needs to be done after all UART clocks are setup */