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linux/drivers/spi/spi-dw.h
Serge Semin bdbdf0f063
spi: dw: Locally wait for the DMA transfers completion 
In general each DMA-based SPI transfer can be split up into two stages:
DMA data transmission/reception and SPI-bus transmission/reception. DMA
asynchronous transactions completion can be tracked by means of the
DMA async Tx-descriptor completion callback. But that callback being
called indicates that the DMA transfer has been finished, it doesn't
mean that SPI data transmission is also done. Moreover in fact it isn't
for at least Tx-only SPI transfers. Upon DMA transfer completion some
data is left in the Tx FIFO and being pushed out by the SPI controller.
So in order to make sure that an SPI transfer is completely pushed to the
SPI-bus, the driver has to wait for both DMA transaction and the SPI-bus
transmission/reception are finished. Note if there is a way to
asynchronously track the former event by means of the DMA async Tx
callback, there isn't easy one for the later (IRQ-based solution won't
work since SPI controller doesn't notify about Rx FIFO being empty).

The DMA transfer completion callback isn't suitable to wait for the
SPI controller activity finish either. The callback might (in case of DW
DMAC it will) be called in the tasklet context. Waiting for the SPI
controller to complete the transfer might take a considerable amount of
time since SPI-bus might be pretty slow. In this case delaying the
execution in the tasklet atomic context might cause significant system
performance drop.

So to speak the best option we've got to solve the problem is to
consequently wait for both stages being finished in the locally
implemented SPI transfer execution procedure even if it costs us of the
local wait-function re-implementation. In this case we don't need to use
the SPI-core transfer-wait functionality, but we'll make sure that
all DMA and SPI-bus transactions are completely finished before the
SPI-core transfer_one callback returns. In this commit we provide an
implementation of the DMA-transfers completion wait functionality.
The DW APB SSI DMA-specific SPI transfer_one function waits for both
Tx and Rx DMA transfers being finished, and only then exits with zero
returned signalling to the SPI core that the SPI transfer is finished.
This implementation is fully equivalent to the currently used
DMA-execution-SPI-core-wait algorithm. The SPI-bus transmission/reception
wait methods will be added in the follow-up commits.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Cc: Georgy Vlasov <Georgy.Vlasov@baikalelectronics.ru>
Cc: Ramil Zaripov <Ramil.Zaripov@baikalelectronics.ru>
Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Feng Tang <feng.tang@intel.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: devicetree@vger.kernel.org
Link: https://lore.kernel.org/r/20200529131205.31838-4-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Mark Brown <broonie@kernel.org>
2020-05-29 15:55:43 +01:00

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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef DW_SPI_HEADER_H
#define DW_SPI_HEADER_H
#include <linux/completion.h>
#include <linux/irqreturn.h>
#include <linux/io.h>
#include <linux/scatterlist.h>
/* Register offsets */
#define DW_SPI_CTRLR0 0x00
#define DW_SPI_CTRLR1 0x04
#define DW_SPI_SSIENR 0x08
#define DW_SPI_MWCR 0x0c
#define DW_SPI_SER 0x10
#define DW_SPI_BAUDR 0x14
#define DW_SPI_TXFTLR 0x18
#define DW_SPI_RXFTLR 0x1c
#define DW_SPI_TXFLR 0x20
#define DW_SPI_RXFLR 0x24
#define DW_SPI_SR 0x28
#define DW_SPI_IMR 0x2c
#define DW_SPI_ISR 0x30
#define DW_SPI_RISR 0x34
#define DW_SPI_TXOICR 0x38
#define DW_SPI_RXOICR 0x3c
#define DW_SPI_RXUICR 0x40
#define DW_SPI_MSTICR 0x44
#define DW_SPI_ICR 0x48
#define DW_SPI_DMACR 0x4c
#define DW_SPI_DMATDLR 0x50
#define DW_SPI_DMARDLR 0x54
#define DW_SPI_IDR 0x58
#define DW_SPI_VERSION 0x5c
#define DW_SPI_DR 0x60
#define DW_SPI_CS_OVERRIDE 0xf4
/* Bit fields in CTRLR0 */
#define SPI_DFS_OFFSET 0
#define SPI_FRF_OFFSET 4
#define SPI_FRF_SPI 0x0
#define SPI_FRF_SSP 0x1
#define SPI_FRF_MICROWIRE 0x2
#define SPI_FRF_RESV 0x3
#define SPI_MODE_OFFSET 6
#define SPI_SCPH_OFFSET 6
#define SPI_SCOL_OFFSET 7
#define SPI_TMOD_OFFSET 8
#define SPI_TMOD_MASK (0x3 << SPI_TMOD_OFFSET)
#define SPI_TMOD_TR 0x0 /* xmit & recv */
#define SPI_TMOD_TO 0x1 /* xmit only */
#define SPI_TMOD_RO 0x2 /* recv only */
#define SPI_TMOD_EPROMREAD 0x3 /* eeprom read mode */
#define SPI_SLVOE_OFFSET 10
#define SPI_SRL_OFFSET 11
#define SPI_CFS_OFFSET 12
/* Bit fields in CTRLR0 based on DWC_ssi_databook.pdf v1.01a */
#define DWC_SSI_CTRLR0_SRL_OFFSET 13
#define DWC_SSI_CTRLR0_TMOD_OFFSET 10
#define DWC_SSI_CTRLR0_TMOD_MASK GENMASK(11, 10)
#define DWC_SSI_CTRLR0_SCPOL_OFFSET 9
#define DWC_SSI_CTRLR0_SCPH_OFFSET 8
#define DWC_SSI_CTRLR0_FRF_OFFSET 6
#define DWC_SSI_CTRLR0_DFS_OFFSET 0
/* Bit fields in SR, 7 bits */
#define SR_MASK 0x7f /* cover 7 bits */
#define SR_BUSY (1 << 0)
#define SR_TF_NOT_FULL (1 << 1)
#define SR_TF_EMPT (1 << 2)
#define SR_RF_NOT_EMPT (1 << 3)
#define SR_RF_FULL (1 << 4)
#define SR_TX_ERR (1 << 5)
#define SR_DCOL (1 << 6)
/* Bit fields in ISR, IMR, RISR, 7 bits */
#define SPI_INT_TXEI (1 << 0)
#define SPI_INT_TXOI (1 << 1)
#define SPI_INT_RXUI (1 << 2)
#define SPI_INT_RXOI (1 << 3)
#define SPI_INT_RXFI (1 << 4)
#define SPI_INT_MSTI (1 << 5)
/* Bit fields in DMACR */
#define SPI_DMA_RDMAE (1 << 0)
#define SPI_DMA_TDMAE (1 << 1)
/* TX RX interrupt level threshold, max can be 256 */
#define SPI_INT_THRESHOLD 32
enum dw_ssi_type {
SSI_MOTO_SPI = 0,
SSI_TI_SSP,
SSI_NS_MICROWIRE,
};
struct dw_spi;
struct dw_spi_dma_ops {
int (*dma_init)(struct device *dev, struct dw_spi *dws);
void (*dma_exit)(struct dw_spi *dws);
int (*dma_setup)(struct dw_spi *dws, struct spi_transfer *xfer);
bool (*can_dma)(struct spi_controller *master, struct spi_device *spi,
struct spi_transfer *xfer);
int (*dma_transfer)(struct dw_spi *dws, struct spi_transfer *xfer);
void (*dma_stop)(struct dw_spi *dws);
};
struct dw_spi {
struct spi_controller *master;
enum dw_ssi_type type;
void __iomem *regs;
unsigned long paddr;
int irq;
u32 fifo_len; /* depth of the FIFO buffer */
u32 max_freq; /* max bus freq supported */
int cs_override;
u32 reg_io_width; /* DR I/O width in bytes */
u16 bus_num;
u16 num_cs; /* supported slave numbers */
void (*set_cs)(struct spi_device *spi, bool enable);
u32 (*update_cr0)(struct spi_controller *master, struct spi_device *spi,
struct spi_transfer *transfer);
/* Current message transfer state info */
size_t len;
void *tx;
void *tx_end;
spinlock_t buf_lock;
void *rx;
void *rx_end;
int dma_mapped;
u8 n_bytes; /* current is a 1/2 bytes op */
irqreturn_t (*transfer_handler)(struct dw_spi *dws);
u32 current_freq; /* frequency in hz */
/* DMA info */
struct dma_chan *txchan;
struct dma_chan *rxchan;
unsigned long dma_chan_busy;
dma_addr_t dma_addr; /* phy address of the Data register */
const struct dw_spi_dma_ops *dma_ops;
struct completion dma_completion;
#ifdef CONFIG_DEBUG_FS
struct dentry *debugfs;
#endif
};
static inline u32 dw_readl(struct dw_spi *dws, u32 offset)
{
return __raw_readl(dws->regs + offset);
}
static inline u16 dw_readw(struct dw_spi *dws, u32 offset)
{
return __raw_readw(dws->regs + offset);
}
static inline void dw_writel(struct dw_spi *dws, u32 offset, u32 val)
{
__raw_writel(val, dws->regs + offset);
}
static inline void dw_writew(struct dw_spi *dws, u32 offset, u16 val)
{
__raw_writew(val, dws->regs + offset);
}
static inline u32 dw_read_io_reg(struct dw_spi *dws, u32 offset)
{
switch (dws->reg_io_width) {
case 2:
return dw_readw(dws, offset);
case 4:
default:
return dw_readl(dws, offset);
}
}
static inline void dw_write_io_reg(struct dw_spi *dws, u32 offset, u32 val)
{
switch (dws->reg_io_width) {
case 2:
dw_writew(dws, offset, val);
break;
case 4:
default:
dw_writel(dws, offset, val);
break;
}
}
static inline void spi_enable_chip(struct dw_spi *dws, int enable)
{
dw_writel(dws, DW_SPI_SSIENR, (enable ? 1 : 0));
}
static inline void spi_set_clk(struct dw_spi *dws, u16 div)
{
dw_writel(dws, DW_SPI_BAUDR, div);
}
/* Disable IRQ bits */
static inline void spi_mask_intr(struct dw_spi *dws, u32 mask)
{
u32 new_mask;
new_mask = dw_readl(dws, DW_SPI_IMR) & ~mask;
dw_writel(dws, DW_SPI_IMR, new_mask);
}
/* Enable IRQ bits */
static inline void spi_umask_intr(struct dw_spi *dws, u32 mask)
{
u32 new_mask;
new_mask = dw_readl(dws, DW_SPI_IMR) | mask;
dw_writel(dws, DW_SPI_IMR, new_mask);
}
/*
* This does disable the SPI controller, interrupts, and re-enable the
* controller back. Transmit and receive FIFO buffers are cleared when the
* device is disabled.
*/
static inline void spi_reset_chip(struct dw_spi *dws)
{
spi_enable_chip(dws, 0);
spi_mask_intr(dws, 0xff);
spi_enable_chip(dws, 1);
}
static inline void spi_shutdown_chip(struct dw_spi *dws)
{
spi_enable_chip(dws, 0);
spi_set_clk(dws, 0);
}
extern void dw_spi_set_cs(struct spi_device *spi, bool enable);
extern int dw_spi_add_host(struct device *dev, struct dw_spi *dws);
extern void dw_spi_remove_host(struct dw_spi *dws);
extern int dw_spi_suspend_host(struct dw_spi *dws);
extern int dw_spi_resume_host(struct dw_spi *dws);
extern u32 dw_spi_update_cr0(struct spi_controller *master,
struct spi_device *spi,
struct spi_transfer *transfer);
extern u32 dw_spi_update_cr0_v1_01a(struct spi_controller *master,
struct spi_device *spi,
struct spi_transfer *transfer);
/* platform related setup */
extern int dw_spi_mid_init_mfld(struct dw_spi *dws);
extern int dw_spi_mid_init_generic(struct dw_spi *dws);
#endif /* DW_SPI_HEADER_H */
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