mcp6x_spi.c: Refactor singleton states into reentrant pattern

Move global singleton states into a struct and store within
the bitbang_spi_master data field for the life-time of the driver.

This patch also drops `mcp6x` and `mcp` prefixes from spi data
struct members.

This is one of the steps on the way to move spi_master data
memory management behind the initialisation API, for more
context see other patches under the same topic "register_master_api".

BUG=b:185191942
TEST=builds

Change-Id: Ia02c1cb9d36fb7b15bb7e09b769d8969c08c2bd5
Signed-off-by: Anastasia Klimchuk <aklm@chromium.org>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/54994
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
diff --git a/mcp6x_spi.c b/mcp6x_spi.c
index de44299..fa309ca 100644
--- a/mcp6x_spi.c
+++ b/mcp6x_spi.c
@@ -36,55 +36,68 @@
 #define MCP6X_SPI_REQUEST	0
 #define MCP6X_SPI_GRANT		8
 
-static void *mcp6x_spibar = NULL;
-
-/* Cached value of last GPIO state. */
-static uint8_t mcp_gpiostate;
+struct mcp6x_spi_data {
+	void *spibar;
+	/* Cached value of last GPIO state. */
+	uint8_t gpiostate;
+};
 
 static void mcp6x_request_spibus(void *spi_data)
 {
-	mcp_gpiostate = mmio_readb(mcp6x_spibar + 0x530);
-	mcp_gpiostate |= 1 << MCP6X_SPI_REQUEST;
-	mmio_writeb(mcp_gpiostate, mcp6x_spibar + 0x530);
+	struct mcp6x_spi_data *data = spi_data;
+
+	data->gpiostate = mmio_readb(data->spibar + 0x530);
+	data->gpiostate |= 1 << MCP6X_SPI_REQUEST;
+	mmio_writeb(data->gpiostate, data->spibar + 0x530);
 
 	/* Wait until we are allowed to use the SPI bus. */
-	while (!(mmio_readw(mcp6x_spibar + 0x530) & (1 << MCP6X_SPI_GRANT))) ;
+	while (!(mmio_readw(data->spibar + 0x530) & (1 << MCP6X_SPI_GRANT))) ;
 
 	/* Update the cache. */
-	mcp_gpiostate = mmio_readb(mcp6x_spibar + 0x530);
+	data->gpiostate = mmio_readb(data->spibar + 0x530);
 }
 
 static void mcp6x_release_spibus(void *spi_data)
 {
-	mcp_gpiostate &= ~(1 << MCP6X_SPI_REQUEST);
-	mmio_writeb(mcp_gpiostate, mcp6x_spibar + 0x530);
+	struct mcp6x_spi_data *data = spi_data;
+
+	data->gpiostate &= ~(1 << MCP6X_SPI_REQUEST);
+	mmio_writeb(data->gpiostate, data->spibar + 0x530);
 }
 
 static void mcp6x_bitbang_set_cs(int val, void *spi_data)
 {
-	mcp_gpiostate &= ~(1 << MCP6X_SPI_CS);
-	mcp_gpiostate |= (val << MCP6X_SPI_CS);
-	mmio_writeb(mcp_gpiostate, mcp6x_spibar + 0x530);
+	struct mcp6x_spi_data *data = spi_data;
+
+	data->gpiostate &= ~(1 << MCP6X_SPI_CS);
+	data->gpiostate |= (val << MCP6X_SPI_CS);
+	mmio_writeb(data->gpiostate, data->spibar + 0x530);
 }
 
 static void mcp6x_bitbang_set_sck(int val, void *spi_data)
 {
-	mcp_gpiostate &= ~(1 << MCP6X_SPI_SCK);
-	mcp_gpiostate |= (val << MCP6X_SPI_SCK);
-	mmio_writeb(mcp_gpiostate, mcp6x_spibar + 0x530);
+	struct mcp6x_spi_data *data = spi_data;
+
+	data->gpiostate &= ~(1 << MCP6X_SPI_SCK);
+	data->gpiostate |= (val << MCP6X_SPI_SCK);
+	mmio_writeb(data->gpiostate, data->spibar + 0x530);
 }
 
 static void mcp6x_bitbang_set_mosi(int val, void *spi_data)
 {
-	mcp_gpiostate &= ~(1 << MCP6X_SPI_MOSI);
-	mcp_gpiostate |= (val << MCP6X_SPI_MOSI);
-	mmio_writeb(mcp_gpiostate, mcp6x_spibar + 0x530);
+	struct mcp6x_spi_data *data = spi_data;
+
+	data->gpiostate &= ~(1 << MCP6X_SPI_MOSI);
+	data->gpiostate |= (val << MCP6X_SPI_MOSI);
+	mmio_writeb(data->gpiostate, data->spibar + 0x530);
 }
 
 static int mcp6x_bitbang_get_miso(void *spi_data)
 {
-	mcp_gpiostate = mmio_readb(mcp6x_spibar + 0x530);
-	return (mcp_gpiostate >> MCP6X_SPI_MISO) & 0x1;
+	struct mcp6x_spi_data *data = spi_data;
+
+	data->gpiostate = mmio_readb(data->spibar + 0x530);
+	return (data->gpiostate >> MCP6X_SPI_MISO) & 0x1;
 }
 
 static const struct bitbang_spi_master bitbang_spi_master_mcp6x = {
@@ -97,11 +110,19 @@
 	.half_period = 0,
 };
 
+static int mcp6x_shutdown(void *spi_data)
+{
+	free(spi_data);
+	return 0;
+}
+
 int mcp6x_spi_init(int want_spi)
 {
 	uint16_t status;
 	uint32_t mcp6x_spibaraddr;
 	struct pci_dev *smbusdev;
+	void *mcp6x_spibar = NULL;
+	uint8_t mcp_gpiostate;
 
 	/* Look for the SMBus device (SMBus PCI class) */
 	smbusdev = pci_dev_find_vendorclass(0x10de, 0x0c05);
@@ -151,7 +172,19 @@
 		 (status >> MCP6X_SPI_GRANT) & 0x1);
 	mcp_gpiostate = status & 0xff;
 
-	if (register_spi_bitbang_master(&bitbang_spi_master_mcp6x, NULL)) {
+	struct mcp6x_spi_data *data = calloc(1, sizeof(*data));
+	if (!data) {
+		msg_perr("Unable to allocate space for SPI master data\n");
+		return 1;
+	}
+	data->spibar = mcp6x_spibar;
+	data->gpiostate = mcp_gpiostate;
+
+	if (register_shutdown(mcp6x_shutdown, data)) {
+		free(data);
+		return 1;
+	}
+	if (register_spi_bitbang_master(&bitbang_spi_master_mcp6x, data)) {
 		/* This should never happen. */
 		msg_perr("MCP6X bitbang SPI master init failed!\n");
 		return 1;