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authorSamir Ibradžić <sibradzic@gmail.com>2012-05-15 22:58:19 +0000
committerStefan Tauner <stefan.tauner@alumni.tuwien.ac.at>2012-05-15 22:58:19 +0000
commitb482c6d5c19bd60385ea7cfb7b889f683a0454e2 (patch)
treee8b1e5c4405905162c711097d21308277170e05c /ft2232_spi.c
parent901a3ba023fd64e29309637f5ad835218e1bb2ac (diff)
downloadast2050-flashrom-b482c6d5c19bd60385ea7cfb7b889f683a0454e2.zip
ast2050-flashrom-b482c6d5c19bd60385ea7cfb7b889f683a0454e2.tar.gz
ft2232_spi.c: add frequency divisor parameter
This adds an optional argument when using the ft2232_spi programmer to set the frequency divisor. The valid values for the divisor is any even integer between 2 and 131072. Corresponding to flashrom svn r1537. Signed-off-by: Samir Ibradžić <sibradzic@gmail.com> Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at> Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Diffstat (limited to 'ft2232_spi.c')
-rw-r--r--ft2232_spi.c54
1 files changed, 37 insertions, 17 deletions
diff --git a/ft2232_spi.c b/ft2232_spi.c
index 122866f..d11867e 100644
--- a/ft2232_spi.c
+++ b/ft2232_spi.c
@@ -64,17 +64,8 @@ const struct usbdev_status devs_ft2232spi[] = {
{},
};
-/*
- * The 'H' chips can run internally at either 12MHz or 60MHz.
- * The non-H chips can only run at 12MHz.
- */
-static uint8_t clock_5x = 1;
-/*
- * In either case, the divisor is a simple integer clock divider.
- * If clock_5x is set, this divisor divides 30MHz, else it divides 6MHz.
- */
-#define DIVIDE_BY 3 /* e.g. '3' will give either 10MHz or 2MHz SPI clock. */
+#define DEFAULT_DIVISOR 2
#define BITMODE_BITBANG_NORMAL 1
#define BITMODE_BITBANG_SPI 2
@@ -162,12 +153,28 @@ static const struct spi_programmer spi_programmer_ft2232 = {
/* Returns 0 upon success, a negative number upon errors. */
int ft2232_spi_init(void)
{
- int f, ret = 0;
+ int ret = 0;
struct ftdi_context *ftdic = &ftdic_context;
unsigned char buf[512];
int ft2232_vid = FTDI_VID;
int ft2232_type = FTDI_FT4232H_PID;
enum ftdi_interface ft2232_interface = INTERFACE_B;
+ /*
+ * The 'H' chips can run with an internal clock of either 12 MHz or 60 MHz,
+ * but the non-H chips can only run at 12 MHz. We enable the divide-by-5
+ * prescaler on the former to run on the same speed.
+ */
+ uint8_t clock_5x = 1;
+ /* In addition to the prescaler mentioned above there is also another
+ * configurable one on all versions of the chips. Its divisor div can be
+ * set by a 16 bit value x according to the following formula:
+ * div = (1 + x) * 2 <-> x = div / 2 - 1
+ * Hence the expressible divisors are all even numbers between 2 and
+ * 2^17 (=131072) resulting in SCK frequencies of 6 MHz down to about
+ * 92 Hz for 12 MHz inputs.
+ */
+ uint32_t divisor = DEFAULT_DIVISOR;
+ int f;
char *arg;
double mpsse_clk;
@@ -243,6 +250,21 @@ int ft2232_spi_init(void)
}
}
free(arg);
+ arg = extract_programmer_param("divisor");
+ if (arg && strlen(arg)) {
+ unsigned int temp = 0;
+ char *endptr;
+ temp = strtoul(arg, &endptr, 10);
+ if (*endptr || temp < 2 || temp > 131072 || temp & 0x1) {
+ msg_perr("Error: Invalid SPI frequency divisor specified: \"%s\".\n"
+ "Valid are even values between 2 and 131072.\n", arg);
+ free(arg);
+ return -2;
+ } else {
+ divisor = (uint32_t)temp;
+ }
+ }
+ free(arg);
msg_pdbg("Using device type %s %s ",
get_ft2232_vendorname(ft2232_vid, ft2232_type),
get_ft2232_devicename(ft2232_vid, ft2232_type));
@@ -303,17 +325,15 @@ int ft2232_spi_init(void)
msg_pdbg("Set clock divisor\n");
buf[0] = 0x86; /* command "set divisor" */
- /* valueL/valueH are (desired_divisor - 1) */
- buf[1] = (DIVIDE_BY - 1) & 0xff;
- buf[2] = ((DIVIDE_BY - 1) >> 8) & 0xff;
if (send_buf(ftdic, buf, 3)) {
ret = -6;
goto ftdi_err;
}
+ buf[1] = (divisor / 2 - 1) & 0xff;
+ buf[2] = ((divisor / 2 - 1) >> 8) & 0xff;
- msg_pdbg("MPSSE clock: %f MHz divisor: %d "
- "SPI clock: %f MHz\n", mpsse_clk, DIVIDE_BY,
- (double)(mpsse_clk / (((DIVIDE_BY - 1) + 1) * 2)));
+ msg_pdbg("MPSSE clock: %f MHz, divisor: %u, SPI clock: %f MHz\n",
+ mpsse_clk, divisor, (double)(mpsse_clk / divisor));
/* Disconnect TDI/DO to TDO/DI for loopback. */
msg_pdbg("No loopback of TDI/DO TDO/DI\n");
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