From 711323e7cc263178090ce28a8901ee1c7fcdff60 Mon Sep 17 00:00:00 2001
From: Joerg Wunsch <j@uriah.heep.sax.de>
Date: Sat, 27 Nov 2021 15:40:12 +0000
Subject: [PATCH] Submitted by Alex Sverdlin: patch #10027: linuxspi: Add reset
 pulse, according to AVR programming algorithm * linuxspi.c (linuxspi_open,
 linuxspi_program_enable): movw out reset code into linuxspi_reset_mcu()

git-svn-id: svn://svn.savannah.nongnu.org/avrdude/trunk/avrdude@1490 81a1dc3b-b13d-400b-aceb-764788c761c2
---
 ChangeLog  |  7 +++++++
 NEWS       |  1 +
 linuxspi.c | 60 ++++++++++++++++++++++++++++++++++++++++++++----------
 3 files changed, 57 insertions(+), 11 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 1a8691df..711e5417 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2021-11-27  Joerg Wunsch <j.gnu@uriah.heep.sax.de>
+
+	Submitted by Alex Sverdlin:
+	patch #10027: linuxspi: Add reset pulse, according to AVR programming algorithm
+	* linuxspi.c (linuxspi_open, linuxspi_program_enable):
+	movw out reset code into linuxspi_reset_mcu()
+
 2021-11-25  Joerg Wunsch <j.gnu@uriah.heep.sax.de>
 
 	Submitted by David Mosberger-Tang:
diff --git a/NEWS b/NEWS
index 21021303..39aea050 100644
--- a/NEWS
+++ b/NEWS
@@ -117,6 +117,7 @@ Current:
     patch #9757: Fix ATtiny817 Xplained Mini programmer
     patch #9327: ft245r.c: add TPI support (patches 1-4)
     patch #9328: ft245r.c: add TPI support (patches 5-7)
+    patch #10027: linuxspi: Add reset pulse, according to AVR programming algorithm
 
   * Internals:
     - New avrdude.conf keyword "family_id", used to verify SIB attributes
diff --git a/linuxspi.c b/linuxspi.c
index 416e89ef..29646e76 100644
--- a/linuxspi.c
+++ b/linuxspi.c
@@ -98,12 +98,32 @@ static void linuxspi_teardown(PROGRAMMER* pgm)
 {
 }
 
+static int linuxspi_reset_mcu(PROGRAMMER *pgm, bool active)
+{
+    struct gpiohandle_data data;
+    int ret;
+
+    /*
+     * Set the reset state and keep it. The pin will be released and set back to
+     * its initial value, once the fd_gpiochip is closed.
+     */
+    data.values[0] = active ^ !(pgm->pinno[PIN_AVR_RESET] & PIN_INVERSE);
+    ret = ioctl(fd_linehandle, GPIOHANDLE_SET_LINE_VALUES_IOCTL, &data);
+    if (ret == -1) {
+        ret = -errno;
+        avrdude_message(MSG_INFO, "%s error: Unable to set GPIO line %d value\n",
+                        progname, pgm->pinno[PIN_AVR_RESET] & ~PIN_INVERSE);
+        return ret;
+    }
+
+    return 0;
+}
+
 static int linuxspi_open(PROGRAMMER *pgm, char *port)
 {
     const char *port_error = "%s: error: Unknown port specification. Please use the format /dev/spidev:/dev/gpiochip[:resetno]\n";
     char *spidev, *gpiochip, *reset_pin;
     struct gpiohandle_request req;
-    struct gpiohandle_data data;
     int ret;
 
     if (!port || !strcmp(port, "unknown")) {
@@ -156,16 +176,9 @@ static int linuxspi_open(PROGRAMMER *pgm, char *port)
 
     fd_linehandle = req.fd;
 
-    /*
-     * Set the reset state and keep it. The pin will be released and set back to
-     * its initial value, once the fd_gpiochip is closed.
-     */
-    data.values[0] = !!(pgm->pinno[PIN_AVR_RESET] & PIN_INVERSE);
-    ret = ioctl(fd_linehandle, GPIOHANDLE_SET_LINE_VALUES_IOCTL, &data);
-    if (ret == -1) {
-        ret = -errno;
+    ret = linuxspi_reset_mcu(pgm, true);
+    if (ret)
         goto close_out;
-    }
 
     return 0;
 
@@ -239,8 +252,33 @@ static int linuxspi_program_enable(PROGRAMMER *pgm, AVRPART *p)
     avr_set_bits(p->op[AVR_OP_PGM_ENABLE], cmd); //set the cmd
     pgm->cmd(pgm, cmd, res);
 
-    if (res[2] != cmd[1])
+    if (res[2] != cmd[1]) {
+        /*
+         * From ATtiny441 datasheet:
+         *
+         * In some systems, the programmer can not guarantee that SCK is held low
+         * during power-up. In this case, RESET must be given a positive pulse after
+         * SCK has been set to '0'. The duration of the pulse must be at least t RST
+         * plus two CPU clock cycles. See Table 25-5 on page 240 for definition of
+         * minimum pulse width on RESET pin, t RST
+         * 2. Wait for at least 20 ms and then enable serial programming by sending
+         * the Programming Enable serial instruction to the MOSI pin
+         * 3. The serial programming instructions will not work if the communication
+         * is out of synchronization. When in sync, the second byte (0x53) will echo
+         * back when issuing the third byte of the Programming Enable instruction
+         * ...
+         * If the 0x53 did not echo back, give RESET a positive pulse and issue a
+         * new Programming Enable command
+         */
+        if (linuxspi_reset_mcu(pgm, false))
+            return -1;
+        usleep(3 + (pgm->baudrate ? 500000 / pgm->baudrate : 1));
+        if (linuxspi_reset_mcu(pgm, true))
+            return -1;
+        usleep(20000);
+
         return -2;
+    }
 
     return 0;
 }