From 28a966a3e66665eaea34b8fc8217a05cfbfcecce Mon Sep 17 00:00:00 2001
From: Uwe Bonnes <bon@elektron.ikp.physik.tu-darmstadt.de>
Date: Fri, 20 Nov 2020 14:07:48 +0100
Subject: [PATCH] frequency: Implement for ftdi.

For all 2232H types, use undivided 60 Mhz.
FIXME: Check FT2322C/D for unsymetric clock at 6 MHz!
---
 src/platforms/hosted/ftdi_bmp.c | 43 +++++++++++++++++++++++++++++++++
 src/platforms/hosted/ftdi_bmp.h |  4 +++
 src/platforms/hosted/platform.c |  5 ++++
 3 files changed, 52 insertions(+)

diff --git a/src/platforms/hosted/ftdi_bmp.c b/src/platforms/hosted/ftdi_bmp.c
index d7ea3d7b..0d15113b 100644
--- a/src/platforms/hosted/ftdi_bmp.c
+++ b/src/platforms/hosted/ftdi_bmp.c
@@ -376,6 +376,18 @@ int ftdi_bmp_init(BMP_CL_OPTIONS_t *cl_opts, bmp_info_t *info)
 	}
 	int index = 0;
 	ftdi_init[index++]= LOOPBACK_END; /* FT2232D gets upset otherwise*/
+	switch(ftdic->type) {
+	case TYPE_2232H:
+	case TYPE_4232H:
+	case TYPE_232H:
+		ftdi_init[index++] = EN_DIV_5;
+		break;
+	case TYPE_2232C:
+		break;
+	default:
+		DEBUG_WARN("FTDI Chip has no MPSSE\n");
+		goto error_2;
+	}
 	ftdi_init[index++]= TCK_DIVISOR;
 	/* Use CLK/2 for about 50 % SWDCLK duty cycle on FT2232c.*/
 	ftdi_init[index++]= 1;
@@ -618,3 +630,34 @@ const char *libftdi_target_voltage(void)
 	}
 	return NULL;
 }
+
+static uint16_t divisor;
+void libftdi_max_frequency_set(uint32_t freq)
+{
+	uint32_t clock;
+	if (ftdic->type == TYPE_2232C)
+		clock = 12 * 1000 * 1000;
+	else
+		/* Undivided clock set during startup*/
+		clock = 60 * 1000 * 1000;
+	uint32_t div = (clock  + 2 * freq - 1)/ freq;
+	if ((div < 4) && (ftdic->type = TYPE_2232C))
+		div = 4; /* Avoid bad unsymetrict FT2232C clock at 6 MHz*/
+	divisor = div / 2 - 1;
+	uint8_t buf[3];
+	buf[0] = TCK_DIVISOR;
+	buf[1] = divisor & 0xff;
+	buf[2] = (divisor >> 8) & 0xff;
+	libftdi_buffer_write(buf, 3);
+}
+
+uint32_t libftdi_max_frequency_get(void)
+{
+	uint32_t clock;
+	if (ftdic->type == TYPE_2232C)
+		clock = 12 * 1000 * 1000;
+	else
+		/* Undivided clock set during startup*/
+		clock = 60 * 1000 * 1000;
+	return clock/ ( 2 *(divisor + 1));
+}
diff --git a/src/platforms/hosted/ftdi_bmp.h b/src/platforms/hosted/ftdi_bmp.h
index 12c90223..ffb9e866 100644
--- a/src/platforms/hosted/ftdi_bmp.h
+++ b/src/platforms/hosted/ftdi_bmp.h
@@ -119,6 +119,8 @@ const char *libftdi_target_voltage(void) {return "ERROR";};
 void libftdi_jtagtap_tdi_tdo_seq(
 	uint8_t *DO, const uint8_t final_tms, const uint8_t *DI, int ticks) {};
 bool  libftdi_swd_possible(bool *do_mpsse, bool *direct_bb_swd) {return false;};
+void libftdi_max_frequency_set(uint32_t freq) {};
+uint32_t libftdi_max_frequency_get(void) {return 0;};
 # pragma GCC diagnostic pop
 #else
 int ftdi_bmp_init(BMP_CL_OPTIONS_t *cl_opts, bmp_info_t *info);
@@ -131,6 +133,8 @@ const char *libftdi_target_voltage(void);
 void libftdi_jtagtap_tdi_tdo_seq(
 	uint8_t *DO, const uint8_t final_tms, const uint8_t *DI, int ticks);
 bool  libftdi_swd_possible(bool *do_mpsse, bool *direct_bb_swd);
+void libftdi_max_frequency_set(uint32_t freq);
+uint32_t libftdi_max_frequency_get(void);
 #endif
 
 #define MPSSE_SK 1
diff --git a/src/platforms/hosted/platform.c b/src/platforms/hosted/platform.c
index 07aab72d..6578327f 100644
--- a/src/platforms/hosted/platform.c
+++ b/src/platforms/hosted/platform.c
@@ -331,6 +331,9 @@ void platform_max_frequency_set(uint32_t freq)
 	case BMP_TYPE_CMSIS_DAP:
 		dap_swj_clock(freq);
 		break;
+	case BMP_TYPE_LIBFTDI:
+		libftdi_max_frequency_set(freq);
+		break;
 	default:
 		DEBUG_WARN("Setting max SWJ frequency not yet implemented\n");
 		break;
@@ -345,6 +348,8 @@ uint32_t platform_max_frequency_get(void)
 	case BMP_TYPE_CMSIS_DAP:
 		return dap_swj_clock(0);
 		break;
+	case BMP_TYPE_LIBFTDI:
+		return libftdi_max_frequency_get();
 	default:
 		DEBUG_WARN("Reading max SWJ frequency not yet implemented\n");
 		break;