[U-Boot] [PATCH v2 5/8] lpc32xx: add LPC32xx SSP support (SPI mode)

[Jagan Teki <jagannadh.teki@gmail.com>]

On 12 February 2015 at 23:07, Albert ARIBAUD (3ADEV)
<albert.aribaud@3adev.fr> wrote:
> Signed-off-by: Albert ARIBAUD (3ADEV) <albert.aribaud@3adev.fr>
> ---
>
> Changes in v2:
> - added MUX setting for SSP0
>
>  arch/arm/cpu/arm926ejs/lpc32xx/devices.c      |  14 +++
>  arch/arm/include/asm/arch-lpc32xx/clk.h       |   3 +
>  arch/arm/include/asm/arch-lpc32xx/sys_proto.h |   1 +
>  drivers/spi/Makefile                          |   1 +
>  drivers/spi/lpc32xx_ssp.c                     | 132 ++++++++++++++++++++++++++
>  5 files changed, 151 insertions(+)
>  create mode 100644 drivers/spi/lpc32xx_ssp.c
>
> diff --git a/arch/arm/cpu/arm926ejs/lpc32xx/devices.c b/arch/arm/cpu/arm926ejs/lpc32xx/devices.c
> index a407098..5a453e3 100644
> --- a/arch/arm/cpu/arm926ejs/lpc32xx/devices.c
> +++ b/arch/arm/cpu/arm926ejs/lpc32xx/devices.c
> @@ -8,11 +8,13 @@
>  #include <asm/arch/cpu.h>
>  #include <asm/arch/clk.h>
>  #include <asm/arch/uart.h>
> +#include <asm/arch/mux.h>
>  #include <asm/io.h>
>  #include <dm.h>
>
>  static struct clk_pm_regs    *clk  = (struct clk_pm_regs *)CLK_PM_BASE;
>  static struct uart_ctrl_regs *ctrl = (struct uart_ctrl_regs *)UART_CTRL_BASE;
> +static struct mux_regs *mux = (struct mux_regs *)MUX_BASE;
>
>  void lpc32xx_uart_init(unsigned int uart_id)
>  {
> @@ -66,3 +68,15 @@ void lpc32xx_i2c_init(unsigned int devnum)
>  U_BOOT_DEVICE(lpc32xx_gpios) = {
>         .name = "gpio_lpc32xx"
>  };
> +
> +/* Mux for SCK0, MISO0, MOSI0. We do not use SSEL0. */
> +
> +#define P_MUX_SET_SSP0 0x1600
> +
> +void lpc32xx_ssp_init(void)
> +{
> +       /* Enable SSP0 interface */
> +       writel(CLK_SSP0_ENABLE_CLOCK, &clk->ssp_ctrl);
> +       /* Mux SSP0 pins */
> +       writel(P_MUX_SET_SSP0, &mux->p_mux_set);
> +}
> diff --git a/arch/arm/include/asm/arch-lpc32xx/clk.h b/arch/arm/include/asm/arch-lpc32xx/clk.h
> index 781ac07..2cb5703 100644
> --- a/arch/arm/include/asm/arch-lpc32xx/clk.h
> +++ b/arch/arm/include/asm/arch-lpc32xx/clk.h
> @@ -155,6 +155,9 @@ struct clk_pm_regs {
>  #define CLK_NAND_MLC                   (1 << 1)
>  #define CLK_NAND_MLC_INT               (1 << 5)
>
> +/* SSP Clock Control Register bits */
> +#define CLK_SSP0_ENABLE_CLOCK          (1 << 0)
> +
>  unsigned int get_sys_clk_rate(void);
>  unsigned int get_hclk_pll_rate(void);
>  unsigned int get_hclk_clk_div(void);
> diff --git a/arch/arm/include/asm/arch-lpc32xx/sys_proto.h b/arch/arm/include/asm/arch-lpc32xx/sys_proto.h
> index a4a05d1..86d5ee9 100644
> --- a/arch/arm/include/asm/arch-lpc32xx/sys_proto.h
> +++ b/arch/arm/include/asm/arch-lpc32xx/sys_proto.h
> @@ -11,5 +11,6 @@ void lpc32xx_uart_init(unsigned int uart_id);
>  void lpc32xx_mac_init(void);
>  void lpc32xx_mlc_nand_init(void);
>  void lpc32xx_i2c_init(unsigned int devnum);
> +void lpc32xx_ssp_init(void);
>
>  #endif /* _LPC32XX_SYS_PROTO_H */
> diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
> index edbd520..ce6f1cc 100644
> --- a/drivers/spi/Makefile
> +++ b/drivers/spi/Makefile
> @@ -32,6 +32,7 @@ obj-$(CONFIG_EXYNOS_SPI) += exynos_spi.o
>  obj-$(CONFIG_FTSSP010_SPI) += ftssp010_spi.o
>  obj-$(CONFIG_ICH_SPI) +=  ich.o
>  obj-$(CONFIG_KIRKWOOD_SPI) += kirkwood_spi.o
> +obj-$(CONFIG_LPC32XX_SSP) += lpc32xx_ssp.o
>  obj-$(CONFIG_MPC52XX_SPI) += mpc52xx_spi.o
>  obj-$(CONFIG_MPC8XXX_SPI) += mpc8xxx_spi.o
>  obj-$(CONFIG_MXC_SPI) += mxc_spi.o
> diff --git a/drivers/spi/lpc32xx_ssp.c b/drivers/spi/lpc32xx_ssp.c
> new file mode 100644
> index 0000000..40270df
> --- /dev/null
> +++ b/drivers/spi/lpc32xx_ssp.c
> @@ -0,0 +1,132 @@
> +/*
> + * 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
> +
> +static struct ssp_regs *ssp0_regs = (struct ssp_regs *)SSP0_BASE;

Pls- use static inline instead of direct macro assignment.

> +
> +static struct spi_slave ssp0_slave = {
> +       .bus = 0,
> +       .cs = 0,
> +       .op_mode_rx = 0,
> +       .op_mode_tx = 0,
> +       .wordlen = 8,
> +       .max_write_size = 1, /* this is for SPI FLASHes -- don't care */
> +       .memory_map = NULL, /* for SPI FLASHes too */
> +       .option = 0,
> +       .flags = 0
> +};

This wouldn't require - spi_alloc_slave() is a generic func to do all the stuff.
See comments below...

> +
> +/* 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)
> +{

Define spi_cs_is_valid() that wikk ensure the controlling bus and cs
options command prompt

use spi_alloc_slave() and members will be having reg_base and slave that's.
See drivers/spi/zynq_spi.c for more info.

Suggested code:
static struct ssp0_spi_slave {
     struct spi_slave slave;
     struct ssp_regs *base;
};

static inline struct ssp0_regs *get_ssp0_spi_base(void)
{
           return (struct ssp0_regs *) SSP0_BASE;
}

in spi_setup_slave()

{
    struct ssp0_spi_slave *ssp0;

    /* valid bus and cs */

    /* allocate */
    ssp0 = spi_alloc_slave(struct ssp0_spi_slave, bus, cs);

    ssp0->base = get_ssp0_spi_base();

}

> +       /* 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;
> +       }
> +
> +       /*
> +        * 8 bit frame, SPI fmt, 500kbps -> clock divider is 26.
> +        * Set SCR to 0 and CPSDVSR to 26.
> +        */
> +
> +       writel(0x7, &ssp0_regs->cr0); /* 8-bit chunks, SPI, 1 clk/bit */
> +       writel(26, &ssp0_regs->cpsr); /* SSP clock = HCLK/26 = 500kbps */
> +       writel(0, &ssp0_regs->imsc); /* do not raise any interrupts */
> +       writel(0, &ssp0_regs->icr); /* clear any pending interrupt */
> +       writel(0, &ssp0_regs->dmacr); /* do not do DMAs */
> +       writel(SSP_CR1_SSP_ENABLE, &ssp0_regs->cr1); /* enable SSP0 */
> +       return &ssp0_slave;
> +}
> +
> +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)
> +{
> +       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(&ssp0_regs->sr);
> +               if ((idx_out < bytelen) && (status & SSP_SR_TNF))
> +                       writel(((u8 *)dout)[idx_out++], &ssp0_regs->data);
> +               if ((idx_in < bytelen) && (status & status & SSP_SR_RNE))
> +                       ((u8 *)din)[idx_in++] = readl(&ssp0_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 */
> +}
> +
> +void spi_free_slave(struct spi_slave *slave)
> +{
> +       /* do nothing */
> +}
> --
> 2.1.0
>

thanks!
-- 
Jagan.