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Diffstat (limited to 'arch/arm/mach-sa1100/ssp.c')
| -rw-r--r-- | arch/arm/mach-sa1100/ssp.c | 240 |
1 files changed, 240 insertions, 0 deletions
diff --git a/arch/arm/mach-sa1100/ssp.c b/arch/arm/mach-sa1100/ssp.c new file mode 100644 index 000000000..613fd767a --- /dev/null +++ b/arch/arm/mach-sa1100/ssp.c @@ -0,0 +1,240 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * linux/arch/arm/mach-sa1100/ssp.c + * + * Copyright (C) 2003 Russell King. + * + * Generic SSP driver. This provides the generic core for simple + * IO-based SSP applications. + */ +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/sched.h> +#include <linux/errno.h> +#include <linux/interrupt.h> +#include <linux/ioport.h> +#include <linux/init.h> +#include <linux/io.h> + +#include <mach/hardware.h> +#include <mach/irqs.h> +#include <asm/hardware/ssp.h> + +#define TIMEOUT 100000 + +static irqreturn_t ssp_interrupt(int irq, void *dev_id) +{ + unsigned int status = Ser4SSSR; + + if (status & SSSR_ROR) + printk(KERN_WARNING "SSP: receiver overrun\n"); + + Ser4SSSR = SSSR_ROR; + + return status ? IRQ_HANDLED : IRQ_NONE; +} + +/** + * ssp_write_word - write a word to the SSP port + * @data: 16-bit, MSB justified data to write. + * + * Wait for a free entry in the SSP transmit FIFO, and write a data + * word to the SSP port. Wait for the SSP port to start sending + * the data. + * + * The caller is expected to perform the necessary locking. + * + * Returns: + * %-ETIMEDOUT timeout occurred + * 0 success + */ +int ssp_write_word(u16 data) +{ + int timeout = TIMEOUT; + + while (!(Ser4SSSR & SSSR_TNF)) { + if (!--timeout) + return -ETIMEDOUT; + cpu_relax(); + } + + Ser4SSDR = data; + + timeout = TIMEOUT; + while (!(Ser4SSSR & SSSR_BSY)) { + if (!--timeout) + return -ETIMEDOUT; + cpu_relax(); + } + + return 0; +} + +/** + * ssp_read_word - read a word from the SSP port + * + * Wait for a data word in the SSP receive FIFO, and return the + * received data. Data is LSB justified. + * + * Note: Currently, if data is not expected to be received, this + * function will wait for ever. + * + * The caller is expected to perform the necessary locking. + * + * Returns: + * %-ETIMEDOUT timeout occurred + * 16-bit data success + */ +int ssp_read_word(u16 *data) +{ + int timeout = TIMEOUT; + + while (!(Ser4SSSR & SSSR_RNE)) { + if (!--timeout) + return -ETIMEDOUT; + cpu_relax(); + } + + *data = (u16)Ser4SSDR; + + return 0; +} + +/** + * ssp_flush - flush the transmit and receive FIFOs + * + * Wait for the SSP to idle, and ensure that the receive FIFO + * is empty. + * + * The caller is expected to perform the necessary locking. + * + * Returns: + * %-ETIMEDOUT timeout occurred + * 0 success + */ +int ssp_flush(void) +{ + int timeout = TIMEOUT * 2; + + do { + while (Ser4SSSR & SSSR_RNE) { + if (!--timeout) + return -ETIMEDOUT; + (void) Ser4SSDR; + } + if (!--timeout) + return -ETIMEDOUT; + } while (Ser4SSSR & SSSR_BSY); + + return 0; +} + +/** + * ssp_enable - enable the SSP port + * + * Turn on the SSP port. + */ +void ssp_enable(void) +{ + Ser4SSCR0 |= SSCR0_SSE; +} + +/** + * ssp_disable - shut down the SSP port + * + * Turn off the SSP port, optionally powering it down. + */ +void ssp_disable(void) +{ + Ser4SSCR0 &= ~SSCR0_SSE; +} + +/** + * ssp_save_state - save the SSP configuration + * @ssp: pointer to structure to save SSP configuration + * + * Save the configured SSP state for suspend. + */ +void ssp_save_state(struct ssp_state *ssp) +{ + ssp->cr0 = Ser4SSCR0; + ssp->cr1 = Ser4SSCR1; + + Ser4SSCR0 &= ~SSCR0_SSE; +} + +/** + * ssp_restore_state - restore a previously saved SSP configuration + * @ssp: pointer to configuration saved by ssp_save_state + * + * Restore the SSP configuration saved previously by ssp_save_state. + */ +void ssp_restore_state(struct ssp_state *ssp) +{ + Ser4SSSR = SSSR_ROR; + + Ser4SSCR0 = ssp->cr0 & ~SSCR0_SSE; + Ser4SSCR1 = ssp->cr1; + Ser4SSCR0 = ssp->cr0; +} + +/** + * ssp_init - setup the SSP port + * + * initialise and claim resources for the SSP port. + * + * Returns: + * %-ENODEV if the SSP port is unavailable + * %-EBUSY if the resources are already in use + * %0 on success + */ +int ssp_init(void) +{ + int ret; + + if (!(PPAR & PPAR_SPR) && (Ser4MCCR0 & MCCR0_MCE)) + return -ENODEV; + + if (!request_mem_region(__PREG(Ser4SSCR0), 0x18, "SSP")) { + return -EBUSY; + } + + Ser4SSSR = SSSR_ROR; + + ret = request_irq(IRQ_Ser4SSP, ssp_interrupt, 0, "SSP", NULL); + if (ret) + goto out_region; + + return 0; + + out_region: + release_mem_region(__PREG(Ser4SSCR0), 0x18); + return ret; +} + +/** + * ssp_exit - undo the effects of ssp_init + * + * release and free resources for the SSP port. + */ +void ssp_exit(void) +{ + Ser4SSCR0 &= ~SSCR0_SSE; + + free_irq(IRQ_Ser4SSP, NULL); + release_mem_region(__PREG(Ser4SSCR0), 0x18); +} + +MODULE_AUTHOR("Russell King"); +MODULE_DESCRIPTION("SA11x0 SSP PIO driver"); +MODULE_LICENSE("GPL"); + +EXPORT_SYMBOL(ssp_write_word); +EXPORT_SYMBOL(ssp_read_word); +EXPORT_SYMBOL(ssp_flush); +EXPORT_SYMBOL(ssp_enable); +EXPORT_SYMBOL(ssp_disable); +EXPORT_SYMBOL(ssp_save_state); +EXPORT_SYMBOL(ssp_restore_state); +EXPORT_SYMBOL(ssp_init); +EXPORT_SYMBOL(ssp_exit); |