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authorAlbert ARIBAUD \(3ADEV\) <albert.aribaud@3adev.fr>2015-03-31 11:40:47 +0200
committerAlbert ARIBAUD <albert.u.boot@aribaud.net>2015-04-10 14:23:20 +0200
commit981219eebe3cc29f155a37951788c18786260514 (patch)
tree00085f2e4a1f7834674720f636a6a82a06e3d897 /drivers/spi/lpc32xx_ssp.c
parent606f7047603422746d112e41937649d44f311af4 (diff)
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lpc32xx: add LPC32xx SSP support (SPI mode)
Reviewed-by: Jagannadha Sutradharudu Teki <jagannadh.teki@gmail.com> Signed-off-by: Albert ARIBAUD (3ADEV) <albert.aribaud@3adev.fr>
Diffstat (limited to 'drivers/spi/lpc32xx_ssp.c')
-rw-r--r--drivers/spi/lpc32xx_ssp.c144
1 files changed, 144 insertions, 0 deletions
diff --git a/drivers/spi/lpc32xx_ssp.c b/drivers/spi/lpc32xx_ssp.c
new file mode 100644
index 0000000..c5b766c
--- /dev/null
+++ b/drivers/spi/lpc32xx_ssp.c
@@ -0,0 +1,144 @@
+/*
+ * LPC32xx SSP interface (SPI mode)
+ *
+ * (C) Copyright 2014 DENX Software Engineering GmbH
+ * Written-by: Albert ARIBAUD <albert.aribaud@3adev.fr>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <common.h>
+#include <linux/compat.h>
+#include <asm/io.h>
+#include <malloc.h>
+#include <spi.h>
+#include <asm/arch/clk.h>
+
+/* SSP chip registers */
+struct ssp_regs {
+ u32 cr0;
+ u32 cr1;
+ u32 data;
+ u32 sr;
+ u32 cpsr;
+ u32 imsc;
+ u32 ris;
+ u32 mis;
+ u32 icr;
+ u32 dmacr;
+};
+
+/* CR1 register defines */
+#define SSP_CR1_SSP_ENABLE 0x0002
+
+/* SR register defines */
+#define SSP_SR_TNF 0x0002
+/* SSP status RX FIFO not empty bit */
+#define SSP_SR_RNE 0x0004
+
+/* lpc32xx spi slave */
+struct lpc32xx_spi_slave {
+ struct spi_slave slave;
+ struct ssp_regs *regs;
+};
+
+static inline struct lpc32xx_spi_slave *to_lpc32xx_spi_slave(
+ struct spi_slave *slave)
+{
+ return container_of(slave, struct lpc32xx_spi_slave, slave);
+}
+
+/* spi_init is called during boot when CONFIG_CMD_SPI is defined */
+void spi_init(void)
+{
+ /*
+ * nothing to do: clocking was enabled in lpc32xx_ssp_enable()
+ * and configuration will be done in spi_setup_slave()
+ */
+}
+
+/* the following is called in sequence by do_spi_xfer() */
+
+struct spi_slave *spi_setup_slave(uint bus, uint cs, uint max_hz, uint mode)
+{
+ struct lpc32xx_spi_slave *lslave;
+
+ /* we only set up SSP0 for now, so ignore bus */
+
+ if (mode & SPI_3WIRE) {
+ error("3-wire mode not supported");
+ return NULL;
+ }
+
+ if (mode & SPI_SLAVE) {
+ error("slave mode not supported\n");
+ return NULL;
+ }
+
+ if (mode & SPI_PREAMBLE) {
+ error("preamble byte skipping not supported\n");
+ return NULL;
+ }
+
+ lslave = spi_alloc_slave(struct lpc32xx_spi_slave, bus, cs);
+ if (!lslave) {
+ printf("SPI_error: Fail to allocate lpc32xx_spi_slave\n");
+ return NULL;
+ }
+
+ lslave->regs = (struct ssp_regs *)SSP0_BASE;
+
+ /*
+ * 8 bit frame, SPI fmt, 500kbps -> clock divider is 26.
+ * Set SCR to 0 and CPSDVSR to 26.
+ */
+
+ writel(0x7, &lslave->regs->cr0); /* 8-bit chunks, SPI, 1 clk/bit */
+ writel(26, &lslave->regs->cpsr); /* SSP clock = HCLK/26 = 500kbps */
+ writel(0, &lslave->regs->imsc); /* do not raise any interrupts */
+ writel(0, &lslave->regs->icr); /* clear any pending interrupt */
+ writel(0, &lslave->regs->dmacr); /* do not do DMAs */
+ writel(SSP_CR1_SSP_ENABLE, &lslave->regs->cr1); /* enable SSP0 */
+ return &lslave->slave;
+}
+
+void spi_free_slave(struct spi_slave *slave)
+{
+ struct lpc32xx_spi_slave *lslave = to_lpc32xx_spi_slave(slave);
+
+ debug("(lpc32xx) spi_free_slave: 0x%08x\n", (u32)lslave);
+ free(lslave);
+}
+
+int spi_claim_bus(struct spi_slave *slave)
+{
+ /* only one bus and slave so far, always available */
+ return 0;
+}
+
+int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
+ const void *dout, void *din, unsigned long flags)
+{
+ struct lpc32xx_spi_slave *lslave = to_lpc32xx_spi_slave(slave);
+ int bytelen = bitlen >> 3;
+ int idx_out = 0;
+ int idx_in = 0;
+ int start_time;
+
+ start_time = get_timer(0);
+ while ((idx_out < bytelen) || (idx_in < bytelen)) {
+ int status = readl(&lslave->regs->sr);
+ if ((idx_out < bytelen) && (status & SSP_SR_TNF))
+ writel(((u8 *)dout)[idx_out++], &lslave->regs->data);
+ if ((idx_in < bytelen) && (status & status & SSP_SR_RNE))
+ ((u8 *)din)[idx_in++] = readl(&lslave->regs->data);
+ if (get_timer(start_time) >= CONFIG_LPC32XX_SSP_TIMEOUT)
+ return -1;
+ }
+ return 0;
+}
+
+void spi_release_bus(struct spi_slave *slave)
+{
+ /* do nothing */
+}