lpc176x: Introduce get_pclock_frequency()

Add get_pclock_frequency() - a standard way of obtaining the
peripheral clock frequency.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

6 files changed, 23 insertions, 12 deletions

diff --git a/src/lpc176x/adc.c b/src/lpc176x/adc.c
index 97e24c16..9eff6e53 100644
--- a/src/lpc176x/adc.c
+++ b/src/lpc176x/adc.c
@@ -1,10 +1,9 @@
 // Analog to digital support on lpc176x
 //
-// Copyright (C) 2018-2019  Kevin O'Connor <kevin@koconnor.net>
+// Copyright (C) 2018-2021  Kevin O'Connor <kevin@koconnor.net>
 //
 // This file may be distributed under the terms of the GNU GPLv3 license.
 
-#include "autoconf.h" // CONFIG_CLOCK_FREQ
 #include "board/armcm_boot.h" // armcm_enable_irq
 #include "board/irq.h" // irq_save
 #include "board/misc.h" // timer_from_us
@@ -67,7 +66,8 @@ gpio_adc_setup(uint8_t pin)
     if (!is_enabled_pclock(PCLK_ADC)) {
         // Power up ADC
         enable_pclock(PCLK_ADC);
-        uint32_t prescal = DIV_ROUND_UP(CONFIG_CLOCK_FREQ, ADC_FREQ_MAX) - 1;
+        uint32_t pclk = get_pclock_frequency(PCLK_ADC);
+        uint32_t prescal = DIV_ROUND_UP(pclk, ADC_FREQ_MAX) - 1;
         LPC_ADC->ADCR = adc_status.adcr = (1<<21) | ((prescal & 0xff) << 8);
         LPC_ADC->ADINTEN = 0xff;
         adc_status.chan = ADC_DONE;
@@ -102,8 +102,9 @@ gpio_adc_sample(struct gpio_adc g)
     adc_status.chan = g.chan;
     LPC_ADC->ADCR = adc_status.adcr | (1 << g.chan) | (1<<16);
 
-need_delay:
-    return ((64 * DIV_ROUND_UP(CONFIG_CLOCK_FREQ, ADC_FREQ_MAX)
+need_delay: ;
+    uint32_t pclk = get_pclock_frequency(PCLK_ADC);
+    return ((64 * DIV_ROUND_UP(pclk, ADC_FREQ_MAX)
              * ARRAY_SIZE(adc_status.samples)) / 4 + timer_from_us(10));
 }
 
diff --git a/src/lpc176x/i2c.c b/src/lpc176x/i2c.c
index 10b45ede..4d8dc361 100644
--- a/src/lpc176x/i2c.c
+++ b/src/lpc176x/i2c.c
@@ -1,6 +1,6 @@
 // I2C functions on lpc176x
 //
-// Copyright (C) 2018  Kevin O'Connor <kevin@koconnor.net>
+// Copyright (C) 2018-2021  Kevin O'Connor <kevin@koconnor.net>
 //
 // This file may be distributed under the terms of the GNU GPLv3 license.
 
@@ -54,7 +54,8 @@ i2c_setup(uint32_t bus, uint32_t rate, uint8_t addr)
 
         // Set 100Khz frequency
         enable_pclock(info->pclk);
-        uint32_t pclk = SystemCoreClock, pulse = pclk / (100000 * 2);
+        uint32_t pclk = get_pclock_frequency(info->pclk);
+        uint32_t pulse = pclk / (100000 * 2);
         i2c->I2SCLL = pulse;
         i2c->I2SCLH = pulse;
 
diff --git a/src/lpc176x/internal.h b/src/lpc176x/internal.h
index a8253138..84b7ac84 100644
--- a/src/lpc176x/internal.h
+++ b/src/lpc176x/internal.h
@@ -19,6 +19,7 @@
 #define PCLK_USB 31
 int is_enabled_pclock(uint32_t pclk);
 void enable_pclock(uint32_t pclk);
+uint32_t get_pclock_frequency(uint32_t pclk);
 void gpio_peripheral(uint32_t gpio, int func, int pullup);
 
 #endif // internal.h
diff --git a/src/lpc176x/main.c b/src/lpc176x/main.c
index 7f19f8c0..b35e31ee 100644
--- a/src/lpc176x/main.c
+++ b/src/lpc176x/main.c
@@ -1,9 +1,10 @@
 // Main starting point for LPC176x boards.
 //
-// Copyright (C) 2018  Kevin O'Connor <kevin@koconnor.net>
+// Copyright (C) 2018-2021  Kevin O'Connor <kevin@koconnor.net>
 //
 // This file may be distributed under the terms of the GNU GPLv3 license.
 
+#include "autoconf.h" // CONFIG_CLOCK_FREQ
 #include "board/armcm_boot.h" // armcm_main
 #include "internal.h" // enable_pclock
 #include "sched.h" // sched_main
@@ -57,6 +58,13 @@ enable_pclock(uint32_t pclk)
     }
 }
 
+// Return the frequency of the given peripheral clock
+uint32_t
+get_pclock_frequency(uint32_t pclk)
+{
+    return CONFIG_CLOCK_FREQ;
+}
+
 // Main entry point - called from armcm_boot.c:ResetHandler()
 void
 armcm_main(void)
diff --git a/src/lpc176x/serial.c b/src/lpc176x/serial.c
index 3d0432ba..63a2bd7d 100644
--- a/src/lpc176x/serial.c
+++ b/src/lpc176x/serial.c
@@ -1,6 +1,6 @@
 // lpc176x serial port
 //
-// Copyright (C) 2018  Kevin O'Connor <kevin@koconnor.net>
+// Copyright (C) 2018-2021  Kevin O'Connor <kevin@koconnor.net>
 //
 // This file may be distributed under the terms of the GNU GPLv3 license.
 
@@ -61,7 +61,7 @@ serial_init(void)
     // Setup baud
     LPC_UART0->LCR = (1<<7); // set DLAB bit
     enable_pclock(PCLK_UART0);
-    uint32_t pclk = SystemCoreClock;
+    uint32_t pclk = get_pclock_frequency(PCLK_UART0);
     uint32_t div = pclk / (CONFIG_SERIAL_BAUD * 16);
     LPC_UART0->DLL = div & 0xff;
     LPC_UART0->DLM = (div >> 8) & 0xff;
diff --git a/src/lpc176x/spi.c b/src/lpc176x/spi.c
index 2e644a1e..582fa77e 100644
--- a/src/lpc176x/spi.c
+++ b/src/lpc176x/spi.c
@@ -1,6 +1,6 @@
 // SPI support on lpc176x
 //
-// Copyright (C) 2018  Kevin O'Connor <kevin@koconnor.net>
+// Copyright (C) 2018-2021  Kevin O'Connor <kevin@koconnor.net>
 //
 // This file may be distributed under the terms of the GNU GPLv3 license.
 
@@ -58,7 +58,7 @@ spi_setup(uint32_t bus, uint8_t mode, uint32_t rate)
 
     // Setup clock rate and mode
     struct spi_config res = {spi_bus[bus].spi, 0, 0};
-    uint32_t pclk = SystemCoreClock;
+    uint32_t pclk = get_pclock_frequency(spi_bus[bus].pclk);
     uint32_t div = DIV_ROUND_UP(pclk/2, rate) << 1;
     res.cpsr = div < 2 ? 2 : (div > 254 ? 254 : div);
     res.cr0 = 0x07 | ((mode & 2) << 5) | ((mode & 1) << 7);