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Code Issues Releases Activity

Add support for Pi 4B, and fix to build on latest Raspbian

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This commit is contained in:
Richard G Hirst 2019-10-01 20:15:55 +01:00
parent 4309bab2ca
commit ff1d383a37
3 changed files with 44 additions and 11 deletions
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11
ServoBlaster/README.txt
View File

@ -120,10 +120,13 @@ card use. This is expected, because the pulse generation is effectively
handled in hardware and not influenced by interrupt latency or scheduling
effects.
The driver uses DMA channel 14, and PWM channel 1. It makes no attempt to
protect against other code using those peripherals. It sets the relevant GPIO
pins to be outputs when the driver is loaded, so please ensure that you are not
driving those pins externally.
The DMA channel used depends on the SOC type. If the Pi has a BCM2711
(Pi4B only, at present) then it uses channel 7; otherwise it uses channel 14.
It uses PWM channel 1. It makes no attempt to protect against other code using
those peripherals. It sets the relevant GPIO pins to be outputs when the
driver is loaded, so please ensure that you are not driving those pins
externally.
I would of course recommend some buffering between the GPIO outputs and the
servo controls, to protect the Pi. That said, I'm living dangerously and doing

1
ServoBlaster/user/mailbox.c
View File

@ -37,6 +37,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include "mailbox.h"

43
ServoBlaster/user/servod.c
View File

@ -70,6 +70,7 @@
#define DMA_CHAN_MIN 0
#define DMA_CHAN_MAX 14
#define DMA_CHAN_DEFAULT 14
#define DMA_CHAN_PI4 7
#define DMA_BASE_OFFSET 0x00007000
#define DMA_LEN DMA_CHAN_SIZE * (DMA_CHAN_MAX+1)
@ -144,6 +145,9 @@
#define PCMCLK_CNTL 38
#define PCMCLK_DIV 39
#define PLLDFREQ_MHZ_DEFAULT 500
#define PLLDFREQ_MHZ_PI4 750
#define DELAY_VIA_PWM 0
#define DELAY_VIA_PCM 1
@ -290,6 +294,13 @@ static uint8_t bplus_p1pin2gpio_map[] = {
21, // P1-40 GPIO 21
};
// bcm_host_get_model_type() return values to name mapping
static const char *model_names[] = {
"A", "B", "A+", "B+", "2B", "Alpha", "CM", "CM2", "3B", "Zero", "CM3",
"Custom", "ZeroW", "3B+", "3A+", "FPGA", "CM3+", "4B"
};
#define NUM_MODELS (sizeof(model_names)/sizeof(*model_names))
// cycle_time_us is the pulse cycle time per servo, in microseconds.
// Typically it should be 20ms, or 20000us.
@ -320,6 +331,7 @@ static int delay_hw = DELAY_VIA_PWM;
static struct timeval *servo_kill_time;
static uint32_t plldfreq_mhz;
static int dma_chan;
static int idle_timeout;
static int invert = 0;
@ -687,9 +699,9 @@ init_hardware(void)
// Initialise PWM
pwm_reg[PWM_CTL] = 0;
udelay(10);
clk_reg[PWMCLK_CNTL] = 0x5A000006; // Source=PLLD (500MHz)
clk_reg[PWMCLK_CNTL] = 0x5A000006; // Source=PLLD (500MHz or 750MHz on Pi4)
udelay(100);
clk_reg[PWMCLK_DIV] = 0x5A000000 | (500<<12); // set pwm div to 500, giving 1MHz
clk_reg[PWMCLK_DIV] = 0x5A000000 | (plldfreq_mhz<<12); // set pwm div to give 1MHz
udelay(100);
clk_reg[PWMCLK_CNTL] = 0x5A000016; // Source=PLLD and enable
udelay(100);
@ -705,9 +717,9 @@ init_hardware(void)
// Initialise PCM
pcm_reg[PCM_CS_A] = 1; // Disable Rx+Tx, Enable PCM block
udelay(100);
clk_reg[PCMCLK_CNTL] = 0x5A000006; // Source=PLLD (500MHz)
clk_reg[PCMCLK_CNTL] = 0x5A000006; // Source=PLLD (500MHz or 750MHz on Pi4)
udelay(100);
clk_reg[PCMCLK_DIV] = 0x5A000000 | (500<<12); // Set pcm div to 500, giving 1MHz
clk_reg[PCMCLK_DIV] = 0x5A000000 | (plldfreq_mhz<<12); // Set pcm div to give 1MHz
udelay(100);
clk_reg[PCMCLK_CNTL] = 0x5A000016; // Source=PLLD and enable
udelay(100);
@ -927,6 +939,8 @@ go_go_go(void)
* digits of the Revision string and treat '00' and '01' as errors, '02' and
* '03' as rev 1, and any other hex value as rev 2. 'Pi1 and Pi2 are
* differentiated by the Hardware being BCM2708 or BCM2709.
*
* NOTE: These days we should just use bcm_host_get_model_type().
*/
static void
get_model_and_revision(void)
@ -977,9 +991,18 @@ get_model_and_revision(void)
else
gpio_cfg = 3;
if (bcm_host_is_model_pi4()) {
plldfreq_mhz = PLLDFREQ_MHZ_PI4;
dma_chan = DMA_CHAN_PI4;
} else {
plldfreq_mhz = PLLDFREQ_MHZ_DEFAULT;
dma_chan = DMA_CHAN_DEFAULT;
}
periph_virt_base = bcm_host_get_peripheral_address();
dram_phys_base = bcm_host_get_sdram_address();
periph_phys_base = 0x7e000000;
/*
* See https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface
*
@ -1287,8 +1310,6 @@ main(int argc, char **argv)
if (*dma_chan_arg < '0' || *dma_chan_arg > '9' ||
*p || dma_chan < DMA_CHAN_MIN || dma_chan > DMA_CHAN_MAX)
fatal("Invalid dma-chan specified\n");
} else {
dma_chan = DMA_CHAN_DEFAULT;
}
if (idle_timeout_arg) {
@ -1358,7 +1379,15 @@ main(int argc, char **argv)
fatal("min value is >= max value\n");
}
printf("\nBoard model: %7d\n", board_model);
{
int bcm_model = bcm_host_get_model_type();
if (bcm_model < NUM_MODELS)
printf("\nBoard model: %7s\n", model_names[bcm_model]);
else
printf("\nBoard model: Unknown\n");
}
printf("GPIO configuration: %s\n", gpio_desc[gpio_cfg]);
printf("Using hardware: %s\n", delay_hw == DELAY_VIA_PWM ? "PWM" : "PCM");
printf("Using DMA channel: %7d\n", dma_chan);