[PATCH 4/5] lpc32xx: Make XTAL OSC freq configurable, add UART input clock selection
Piotr Wojtaszczyk
piotr.wojtaszczyk at timesys.com
Fri Jan 26 10:25:31 CET 2024
Allow to configure external XTAL OSC or external clock frequency.
Add source clock selection for UART, selecting HCLK may be needed for
higher clock resolution for specific XTAL OSC and baud rate combinations.
HSUART is always driven by PERIPH_CLK.
Signed-off-by: Piotr Wojtaszczyk <piotr.wojtaszczyk at timesys.com>
---
arch/arm/include/asm/arch-lpc32xx/clk.h | 3 +-
arch/arm/include/asm/arch-lpc32xx/config.h | 2 +-
arch/arm/mach-lpc32xx/Kconfig | 23 +++++++++++++
arch/arm/mach-lpc32xx/clk.c | 8 +++--
arch/arm/mach-lpc32xx/devices.c | 38 +++++++++++++++++-----
5 files changed, 60 insertions(+), 14 deletions(-)
diff --git a/arch/arm/include/asm/arch-lpc32xx/clk.h b/arch/arm/include/asm/arch-lpc32xx/clk.h
index 5ab48a9d3c..75dce06104 100644
--- a/arch/arm/include/asm/arch-lpc32xx/clk.h
+++ b/arch/arm/include/asm/arch-lpc32xx/clk.h
@@ -8,8 +8,7 @@
#include <asm/types.h>
-#define OSC_CLK_FREQUENCY 13000000
-#define RTC_CLK_FREQUENCY 32768
+#define LPC32XX_RTC_CLK_FREQUENCY 32768
/* Clocking and Power Control Registers */
struct clk_pm_regs {
diff --git a/arch/arm/include/asm/arch-lpc32xx/config.h b/arch/arm/include/asm/arch-lpc32xx/config.h
index 41160384a4..836e29bd96 100644
--- a/arch/arm/include/asm/arch-lpc32xx/config.h
+++ b/arch/arm/include/asm/arch-lpc32xx/config.h
@@ -12,7 +12,7 @@
/* Basic CPU architecture */
#if !defined(CFG_SYS_NS16550_CLK)
-#define CFG_SYS_NS16550_CLK 13000000
+#define CFG_SYS_NS16550_CLK get_serial_clock()
#endif
#define CFG_SYS_BAUDRATE_TABLE \
diff --git a/arch/arm/mach-lpc32xx/Kconfig b/arch/arm/mach-lpc32xx/Kconfig
index 185bda41c2..6b54ec6220 100644
--- a/arch/arm/mach-lpc32xx/Kconfig
+++ b/arch/arm/mach-lpc32xx/Kconfig
@@ -17,6 +17,29 @@ config TARGET_EA_LPC3250DEVKITV2
endchoice
+choice
+ prompt "LPC32xx clock source for standard UARTs"
+ help
+ Select clock source for standard UART baudrate divider.
+
+config LPC32XX_UART_PERIPH_CLK
+ bool "PERIPH as clock source"
+ help
+ Slower than HCLK, less resolution, lower power consumption.
+
+config LPC32XX_UART_HCLK_CLK
+ bool "HCLK as clock source"
+ help
+ Faster than PERIPH, better resolution, higher power consumption.
+
+endchoice
+
+config LPC32XX_OSC_CLK_FREQUENCY
+ int "LPC32xx external XTAL OSC or clock source frequency"
+ default 13000000
+ help
+ LPC32xx external XTAL OSC or clock source frequency.
+
source "board/timll/devkit3250/Kconfig"
source "board/work-microwave/work_92105/Kconfig"
source "board/ea/ea-lpc3250devkitv2/Kconfig"
diff --git a/arch/arm/mach-lpc32xx/clk.c b/arch/arm/mach-lpc32xx/clk.c
index cb2344d79f..f327e0e876 100644
--- a/arch/arm/mach-lpc32xx/clk.c
+++ b/arch/arm/mach-lpc32xx/clk.c
@@ -15,9 +15,9 @@ static struct clk_pm_regs *clk = (struct clk_pm_regs *)CLK_PM_BASE;
unsigned int get_sys_clk_rate(void)
{
if (readl(&clk->sysclk_ctrl) & CLK_SYSCLK_PLL397)
- return RTC_CLK_FREQUENCY * 397;
+ return LPC32XX_RTC_CLK_FREQUENCY * 397;
else
- return OSC_CLK_FREQUENCY;
+ return CONFIG_LPC32XX_OSC_CLK_FREQUENCY;
}
unsigned int get_hclk_pll_rate(void)
@@ -134,5 +134,9 @@ unsigned int get_sdram_clk_rate(void)
int get_serial_clock(void)
{
+#if IS_ENABLED(CONFIG_LPC32XX_UART_HCLK_CLK)
+ return get_hclk_clk_rate();
+#else
return get_periph_clk_rate();
+#endif
}
diff --git a/arch/arm/mach-lpc32xx/devices.c b/arch/arm/mach-lpc32xx/devices.c
index 6a67a3591a..27061b6212 100644
--- a/arch/arm/mach-lpc32xx/devices.c
+++ b/arch/arm/mach-lpc32xx/devices.c
@@ -6,6 +6,7 @@
#include <common.h>
#include <dm.h>
#include <ns16550.h>
+#include <clock_legacy.h>
#include <asm/arch/clk.h>
#include <asm/arch/uart.h>
@@ -16,6 +17,13 @@ static struct clk_pm_regs *clk = (struct clk_pm_regs *)CLK_PM_BASE;
static struct uart_ctrl_regs *ctrl = (struct uart_ctrl_regs *)UART_CTRL_BASE;
static struct mux_regs *mux = (struct mux_regs *)MUX_BASE;
+#define LPC32XX_USB_RATE 1000000
+#define LPC32XX_USB_DIV ((CONFIG_LPC32XX_OSC_CLK_FREQUENCY/LPC32XX_USB_RATE)-1)
+
+#if !CONFIG_IS_ENABLED(OF_CONTROL)
+static struct ns16550_plat lpc32xx_uart[4];
+#endif
+
void lpc32xx_uart_init(unsigned int uart_id)
{
if (uart_id < 1 || uart_id > 7)
@@ -36,20 +44,30 @@ void lpc32xx_uart_init(unsigned int uart_id)
UART_CLKMODE_AUTO(uart_id));
/* Bypass pre-divider of UART clock */
+#if IS_ENABLED(CONFIG_LPC32XX_UART_HCLK_CLK)
+ /* Use HCLK as input for baudrate divider */
+ writel(CLK_UART_HCLK | CLK_UART_X_DIV(1) | CLK_UART_Y_DIV(1),
+ &clk->u3clk + (uart_id - 3));
+#else
+ /* Use PERIPH as input for baudrate divider */
writel(CLK_UART_X_DIV(1) | CLK_UART_Y_DIV(1),
&clk->u3clk + (uart_id - 3));
+#endif
+
+#if !CONFIG_IS_ENABLED(OF_CONTROL)
+ int i;
+ for (i = 0; i < ARRAY_SIZE(lpc32xx_uart); i++) {
+ lpc32xx_uart[i].clock = get_serial_clock();
+ }
+#endif
}
#if !CONFIG_IS_ENABLED(OF_CONTROL)
-static const struct ns16550_plat lpc32xx_uart[] = {
- { .base = UART3_BASE, .reg_shift = 2,
- .clock = CFG_SYS_NS16550_CLK, .fcr = UART_FCR_DEFVAL, },
- { .base = UART4_BASE, .reg_shift = 2,
- .clock = CFG_SYS_NS16550_CLK, .fcr = UART_FCR_DEFVAL, },
- { .base = UART5_BASE, .reg_shift = 2,
- .clock = CFG_SYS_NS16550_CLK, .fcr = UART_FCR_DEFVAL, },
- { .base = UART6_BASE, .reg_shift = 2,
- .clock = CFG_SYS_NS16550_CLK, .fcr = UART_FCR_DEFVAL, },
+static struct ns16550_plat lpc32xx_uart[] = {
+ { .base = UART3_BASE, .reg_shift = 2, .fcr = UART_FCR_DEFVAL, },
+ { .base = UART4_BASE, .reg_shift = 2, .fcr = UART_FCR_DEFVAL, },
+ { .base = UART5_BASE, .reg_shift = 2, .fcr = UART_FCR_DEFVAL, },
+ { .base = UART6_BASE, .reg_shift = 2, .fcr = UART_FCR_DEFVAL, },
};
U_BOOT_DRVINFOS(lpc32xx_uarts) = {
@@ -94,6 +112,8 @@ void lpc32xx_usb_init(void)
{
/* Do not route the UART 5 Tx/Rx pins to the USB D+ and USB D- pins. */
clrbits_le32(&ctrl->ctrl, UART_CTRL_UART5_USB_MODE);
+
+ writel(LPC32XX_USB_DIV, &clk->usbdiv_ctrl);
}
void lpc32xx_i2c_init(unsigned int devnum)
--
2.25.1
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