[PATCH v9 2/2] board: sl28: add board specific nvm command

[Michael Walle <michael@walle.cc>]

The board supports 16 configuration bits which can be manipulated with
this command. See the board's README for a detailed explanation on each
bit.

Signed-off-by: Michael Walle <michael@walle.cc>
Tested-by: Heiko Thiery <heiko.thiery@gmail.com>
---
 board/kontron/sl28/Makefile |   2 +-
 board/kontron/sl28/cmds.c   | 178 ++++++++++++++++++++++++++++++++++++
 2 files changed, 179 insertions(+), 1 deletion(-)
 create mode 100644 board/kontron/sl28/cmds.c

diff --git a/board/kontron/sl28/Makefile b/board/kontron/sl28/Makefile
index 0f1866c874..74d8012f0f 100644
--- a/board/kontron/sl28/Makefile
+++ b/board/kontron/sl28/Makefile
@@ -1,7 +1,7 @@
 # SPDX-License-Identifier:	GPL-2.0+
 
 ifndef CONFIG_SPL_BUILD
-obj-y += sl28.o
+obj-y += sl28.o cmds.o
 endif
 
 obj-y += common.o ddr.o
diff --git a/board/kontron/sl28/cmds.c b/board/kontron/sl28/cmds.c
new file mode 100644
index 0000000000..046d3b4903
--- /dev/null
+++ b/board/kontron/sl28/cmds.c
@@ -0,0 +1,178 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * sl28 extension commands
+ *
+ * Copyright (c) 2020 Kontron Europe GmbH
+ */
+
+#include <common.h>
+#include <command.h>
+#include <i2c.h>
+#include <linux/delay.h>
+
+#define CPLD_I2C_ADDR 0x4a
+#define REG_UFM_CTRL 0x02
+#define   UFM_CTRL_DCLK    BIT(1)
+#define   UFM_CTRL_DIN     BIT(2)
+#define   UFM_CTRL_PROGRAM BIT(3)
+#define   UFM_CTRL_ERASE   BIT(4)
+#define   UFM_CTRL_DSHIFT  BIT(5)
+#define   UFM_CTRL_DOUT    BIT(6)
+#define   UFM_CTRL_BUSY    BIT(7)
+
+static int ufm_shift_data(struct udevice *dev, u16 data_in, u16 *data_out)
+{
+	int i;
+	int ret;
+	u16 data = 0;
+
+	/* latch data */
+	ret = dm_i2c_reg_write(dev, REG_UFM_CTRL, 0);
+	if (ret < 0)
+		return ret;
+	ret = dm_i2c_reg_write(dev, REG_UFM_CTRL, UFM_CTRL_DCLK);
+	if (ret < 0)
+		return ret;
+
+	/* assert drshift */
+	ret = dm_i2c_reg_write(dev, REG_UFM_CTRL,
+			       UFM_CTRL_DSHIFT | UFM_CTRL_DCLK);
+	if (ret < 0)
+		return ret;
+
+	/* clock 16 data bits, reverse order */
+	for (i = 15; i >= 0; i--) {
+		u8 din = (data_in & (1 << i)) ? UFM_CTRL_DIN : 0;
+
+		ret = dm_i2c_reg_write(dev, REG_UFM_CTRL, UFM_CTRL_DSHIFT
+				| din);
+		if (ret < 0)
+			return ret;
+		if (data_out) {
+			ret = dm_i2c_reg_read(dev, REG_UFM_CTRL);
+			if (ret < 0)
+				return ret;
+			if (ret & UFM_CTRL_DOUT)
+				data |= (1 << i);
+		}
+		ret = dm_i2c_reg_write(dev, REG_UFM_CTRL,
+				       UFM_CTRL_DSHIFT | UFM_CTRL_DCLK | din);
+		if (ret < 0)
+			return ret;
+	}
+
+	/* deassert drshift */
+	ret = dm_i2c_reg_write(dev, REG_UFM_CTRL, UFM_CTRL_DCLK);
+	if (ret < 0)
+		return ret;
+
+	if (data_out)
+		*data_out = data;
+
+	return ret;
+}
+
+static int ufm_erase(struct udevice *dev)
+{
+	int ret;
+
+	/* erase, tEPMX is 500ms */
+	ret = dm_i2c_reg_write(dev, REG_UFM_CTRL,
+			       UFM_CTRL_DCLK | UFM_CTRL_ERASE);
+	if (ret < 0)
+		return ret;
+	ret = dm_i2c_reg_write(dev, REG_UFM_CTRL, UFM_CTRL_DCLK);
+	if (ret < 0)
+		return ret;
+	mdelay(500);
+
+	return 0;
+}
+
+static int ufm_program(struct udevice *dev)
+{
+	int ret;
+
+	/* program, tPPMX is 100us */
+	ret = dm_i2c_reg_write(dev, REG_UFM_CTRL,
+			       UFM_CTRL_DCLK | UFM_CTRL_PROGRAM);
+	if (ret < 0)
+		return ret;
+	ret = dm_i2c_reg_write(dev, REG_UFM_CTRL, UFM_CTRL_DCLK);
+	if (ret < 0)
+		return ret;
+	udelay(100);
+
+	return 0;
+}
+
+static int ufm_write(struct udevice *dev, u16 data)
+{
+	int ret;
+
+	ret = ufm_shift_data(dev, data, NULL);
+	if (ret < 0)
+		return ret;
+
+	ret = ufm_erase(dev);
+	if (ret < 0)
+		return ret;
+
+	return ufm_program(dev);
+}
+
+static int ufm_read(struct udevice *dev, u16 *data)
+{
+	return ufm_shift_data(dev, 0, data);
+}
+
+static int do_sl28_nvm(struct cmd_tbl *cmdtp, int flag, int argc,
+		       char *const argv[])
+{
+	struct udevice *dev;
+	u16 nvm;
+	int ret;
+	char *endp;
+
+	if (i2c_get_chip_for_busnum(0, CPLD_I2C_ADDR, 1, &dev))
+		return CMD_RET_FAILURE;
+
+	if (argc > 1) {
+		nvm = simple_strtoul(argv[1], &endp, 16);
+		if (*endp != '\0') {
+			printf("ERROR: argument is not a valid number\n");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		/*
+		 * We swap all bits, because the a zero bit in hardware means the
+		 * feature is enabled. But this is hard for the user.
+		 */
+		nvm ^= 0xffff;
+
+		ret = ufm_write(dev, nvm);
+		if (ret)
+			goto out;
+		printf("New settings will be activated after the next power cycle!\n");
+	} else {
+		ret = ufm_read(dev, &nvm);
+		if (ret)
+			goto out;
+		nvm ^= 0xffff;
+
+		printf("%04hx\n", nvm);
+	}
+
+	return CMD_RET_SUCCESS;
+
+out:
+	printf("command failed (%d)\n", ret);
+	return CMD_RET_FAILURE;
+}
+
+static char sl28_help_text[] =
+	"nvm [<hex>] - display/set the 16 non-volatile bits\n";
+
+U_BOOT_CMD_WITH_SUBCMDS(sl28, "SMARC-sAL28 specific", sl28_help_text,
+			U_BOOT_SUBCMD_MKENT(nvm, 2, 1, do_sl28_nvm));
-- 
2.20.1