acpi: Add support for writing a GPIO power sequence

Power to some devices is controlled by GPIOs. Add a way to generate ACPI
code to enable and disable a GPIO so that this can be handled within an
ACPI method.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

3 files changed, 205 insertions, 0 deletions

diff --git a/include/acpi/acpigen.h b/include/acpi/acpigen.h
index 2c07a56208..d06d2c0c73 100644
--- a/include/acpi/acpigen.h
+++ b/include/acpi/acpigen.h
@@ -13,6 +13,7 @@
 #include <linux/types.h>
 
 struct acpi_ctx;
+struct acpi_gpio;
 
 /* Top 4 bits of the value used to indicate a three-byte length value */
 #define ACPI_PKG_LEN_3_BYTES	0x80
@@ -343,4 +344,59 @@ void acpigen_write_power_res(struct acpi_ctx *ctx, const char *name, uint level,
 			     uint order, const char *const dev_states[],
 			     size_t dev_states_count);
 
+/**
+ * acpigen_set_enable_tx_gpio() - Emit ACPI code to enable/disable a GPIO
+ *
+ * This emits code to either enable to disable a Tx GPIO. It takes account of
+ * the GPIO polarity.
+ *
+ * The code needs access to the DW0 register for the pad being used. This is
+ * provided by gpio->pin0_addr and ACPI methods must be defined for the board
+ * which can read and write the pad's DW0 register given this address:
+ *    @dw0_read: takes a single argument, the DW0 address
+ *		 returns the DW0 value
+ *    @dw0:write: takes two arguments, the DW0 address and the value to write
+ *		 no return value
+ *
+ * Example code (-- means comment):
+ *
+ *	-- Get Pad Configuration DW0 register value
+ *	Method (GPC0, 0x1, Serialized)
+ *	{
+ *		-- Arg0 - GPIO DW0 address
+ *		Store (Arg0, Local0)
+ *		OperationRegion (PDW0, SystemMemory, Local0, 4)
+ *		Field (PDW0, AnyAcc, NoLock, Preserve) {
+ *			TEMP, 32
+ *		}
+ *		Return (TEMP)
+ *	}
+ *
+ *	-- Set Pad Configuration DW0 register value
+ *	Method (SPC0, 0x2, Serialized)
+ *	{
+ *		-- Arg0 - GPIO DW0 address
+ *		-- Arg1 - Value for DW0 register
+ *		Store (Arg0, Local0)
+ *		OperationRegion (PDW0, SystemMemory, Local0, 4)
+ *		Field (PDW0, AnyAcc, NoLock, Preserve) {
+ *			TEMP,32
+ *		}
+ *		Store (Arg1, TEMP)
+ *	}
+ *
+ *
+ * @ctx: ACPI context pointer
+ * @tx_state_val: Mask to use to toggle the TX state on the GPIO pin, e,g.
+ *	PAD_CFG0_TX_STATE
+ * @dw0_read: Method name to use to read dw0, e.g. "\\_SB.GPC0"
+ * @dw0_write: Method name to use to read dw0, e.g. "\\_SB.SPC0"
+ * @gpio: GPIO to change
+ * @enable: true to enable GPIO, false to disable
+ * Returns 0 on success, -ve on error.
+ */
+int acpigen_set_enable_tx_gpio(struct acpi_ctx *ctx, u32 tx_state_val,
+			       const char *dw0_read, const char *dw0_write,
+			       struct acpi_gpio *gpio, bool enable);
+
 #endif
diff --git a/lib/acpi/acpigen.c b/lib/acpi/acpigen.c
index 70d734245b..45216c1f9d 100644
--- a/lib/acpi/acpigen.c
+++ b/lib/acpi/acpigen.c
@@ -13,6 +13,7 @@
 #include <log.h>
 #include <uuid.h>
 #include <acpi/acpigen.h>
+#include <acpi/acpi_device.h>
 #include <dm/acpi.h>
 
 u8 *acpigen_get_current(struct acpi_ctx *ctx)
@@ -395,3 +396,87 @@ void acpigen_write_debug_string(struct acpi_ctx *ctx, const char *str)
 	acpigen_write_string(ctx, str);
 	acpigen_emit_ext_op(ctx, DEBUG_OP);
 }
+
+/**
+ * acpigen_get_dw0_in_local5() - Generate code to put dw0 cfg0 in local5
+ *
+ * Store (\_SB.GPC0 (addr), Local5)
+ *
+ * \_SB.GPC0 is used to read cfg0 value from dw0. It is typically defined in
+ * the board's gpiolib.asl
+ *
+ * The value needs to be stored in a local variable so that it can be used in
+ * expressions in the ACPI code.
+ *
+ * @ctx: ACPI context pointer
+ * @dw0_read: Name to use to read dw0, e.g. "\\_SB.GPC0"
+ * @addr: GPIO pin configuration register address
+ *
+ */
+static void acpigen_get_dw0_in_local5(struct acpi_ctx *ctx,
+				      const char *dw0_read, ulong addr)
+{
+	acpigen_write_store(ctx);
+	acpigen_emit_namestring(ctx, dw0_read);
+	acpigen_write_integer(ctx, addr);
+	acpigen_emit_byte(ctx, LOCAL5_OP);
+}
+
+/**
+ * acpigen_set_gpio_val() - Emit code to set value of TX GPIO to on/off
+ *
+ * @ctx: ACPI context pointer
+ * @dw0_read: Method name to use to read dw0, e.g. "\\_SB.GPC0"
+ * @dw0_write: Method name to use to read dw0, e.g. "\\_SB.SPC0"
+ * @gpio_num: GPIO number to adjust
+ * @vaL: true to set on, false to set off
+ */
+static int acpigen_set_gpio_val(struct acpi_ctx *ctx, u32 tx_state_val,
+				const char *dw0_read, const char *dw0_write,
+				struct acpi_gpio *gpio, bool val)
+{
+	acpigen_get_dw0_in_local5(ctx, dw0_read, gpio->pin0_addr);
+
+	/* Store (0x40, Local0) */
+	acpigen_write_store(ctx);
+	acpigen_write_integer(ctx, tx_state_val);
+	acpigen_emit_byte(ctx, LOCAL0_OP);
+
+	if (val) {
+		/* Or (Local5, PAD_CFG0_TX_STATE, Local5) */
+		acpigen_write_or(ctx, LOCAL5_OP, LOCAL0_OP, LOCAL5_OP);
+	} else {
+		/* Not (PAD_CFG0_TX_STATE, Local6) */
+		acpigen_write_not(ctx, LOCAL0_OP, LOCAL6_OP);
+
+		/* And (Local5, Local6, Local5) */
+		acpigen_write_and(ctx, LOCAL5_OP, LOCAL6_OP, LOCAL5_OP);
+	}
+
+	/*
+	 * \_SB.SPC0 (addr, Local5)
+	 * \_SB.SPC0 is used to write cfg0 value in dw0. It is defined in
+	 * gpiolib.asl.
+	 */
+	acpigen_emit_namestring(ctx, dw0_write);
+	acpigen_write_integer(ctx, gpio->pin0_addr);
+	acpigen_emit_byte(ctx, LOCAL5_OP);
+
+	return 0;
+}
+
+int acpigen_set_enable_tx_gpio(struct acpi_ctx *ctx, u32 tx_state_val,
+			       const char *dw0_read, const char *dw0_write,
+			       struct acpi_gpio *gpio, bool enable)
+{
+	bool set;
+	int ret;
+
+	set = gpio->polarity == ACPI_GPIO_ACTIVE_HIGH ? enable : !enable;
+	ret = acpigen_set_gpio_val(ctx, tx_state_val, dw0_read, dw0_write, gpio,
+				   set);
+	if (ret)
+		return log_msg_ret("call", ret);
+
+	return 0;
+}
diff --git a/test/dm/acpigen.c b/test/dm/acpigen.c
index df062a210c..9b699fc26a 100644
--- a/test/dm/acpigen.c
+++ b/test/dm/acpigen.c
@@ -742,3 +742,67 @@ static int dm_test_acpi_power_res(struct unit_test_state *uts)
 	return 0;
 }
 DM_TEST(dm_test_acpi_power_res, 0);
+
+/* Test writing ACPI code to toggle a GPIO */
+static int dm_test_acpi_gpio_toggle(struct unit_test_state *uts)
+{
+	const uint addr = 0x80012;
+	const int txbit = BIT(2);
+	struct gpio_desc desc;
+	struct acpi_gpio gpio;
+	struct acpi_ctx *ctx;
+	struct udevice *dev;
+	u8 *ptr;
+
+	ut_assertok(alloc_context(&ctx));
+
+	ut_assertok(uclass_get_device(UCLASS_TEST_FDT, 0, &dev));
+	ut_asserteq_str("a-test", dev->name);
+	ut_assertok(gpio_request_by_name(dev, "test2-gpios", 2, &desc, 0));
+	ut_assertok(gpio_get_acpi(&desc, &gpio));
+
+	/* Spot-check the results - see sb_gpio_get_acpi() */
+	ptr = acpigen_get_current(ctx);
+	acpigen_set_enable_tx_gpio(ctx, txbit, "\\_SB.GPC0", "\\_SB.SPC0",
+				   &gpio, true);
+	acpigen_set_enable_tx_gpio(ctx, txbit, "\\_SB.GPC0", "\\_SB.SPC0",
+				   &gpio, false);
+
+	/* Since this GPIO is active low, we expect it to be cleared here */
+	ut_asserteq(STORE_OP, *ptr);
+	ut_asserteq_strn("_SB_GPC0", (char *)ptr + 3);
+	ut_asserteq(addr + desc.offset, get_unaligned((u32 *)(ptr + 0xc)));
+	ut_asserteq(LOCAL5_OP, ptr[0x10]);
+
+	ut_asserteq(STORE_OP, ptr[0x11]);
+	ut_asserteq(BYTE_PREFIX, ptr[0x12]);
+	ut_asserteq(txbit, ptr[0x13]);
+	ut_asserteq(LOCAL0_OP, ptr[0x14]);
+
+	ut_asserteq(NOT_OP, ptr[0x15]);
+	ut_asserteq(LOCAL0_OP, ptr[0x16]);
+	ut_asserteq(LOCAL6_OP, ptr[0x17]);
+	ut_asserteq(AND_OP, ptr[0x18]);
+	ut_asserteq_strn("_SB_SPC0", (char *)ptr + 0x1e);
+	ut_asserteq(addr + desc.offset, get_unaligned((u32 *)(ptr + 0x27)));
+	ut_asserteq(LOCAL5_OP, ptr[0x2b]);
+
+	/* Now the second one, which should be set */
+	ut_asserteq_strn("_SB_GPC0", (char *)ptr + 0x2f);
+	ut_asserteq(addr + desc.offset, get_unaligned((u32 *)(ptr + 0x38)));
+	ut_asserteq(LOCAL5_OP, ptr[0x3c]);
+
+	ut_asserteq(STORE_OP, ptr[0x3d]);
+
+	ut_asserteq(OR_OP, ptr[0x41]);
+	ut_asserteq(LOCAL0_OP, ptr[0x43]);
+	ut_asserteq_strn("_SB_SPC0", (char *)ptr + 0x47);
+	ut_asserteq(addr + desc.offset, get_unaligned((u32 *)(ptr + 0x50)));
+	ut_asserteq(LOCAL5_OP, ptr[0x54]);
+	ut_asserteq(0x55, acpigen_get_current(ctx) - ptr);
+
+	free_context(&ctx);
+
+	return 0;
+}
+DM_TEST(dm_test_acpi_gpio_toggle, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);