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u-boot/drivers/video/ssd2828.c
Siarhei Siamashka dddccd6913 video: ssd2828: Allow using 'pclk' as the PLL clock source 
Instead of using the internal 'tx_clk' clock source, it is also
possible to use the pixel clock signal from the parallel LCD
interface ('pclk') as the reference clock for PLL.

The 'tx_clk' clock speed may be different on different boards/devices
(the allowed range is 8MHz - 30MHz). Which is not very convenient,
especially considering the need to know the exact 'tx_clk' clock
speed. This clock speed may be difficult to identify without having
device schematics and/or accurate documentation/sources every time.

Using 'pclk' is free from all these problems.

Signed-off-by: Siarhei Siamashka <siarhei.siamashka@gmail.com>
Acked-by: Anatolij Gustschin <agust@denx.de>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
2015-01-22 12:34:56 +01:00

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/*
* (C) 2015 Siarhei Siamashka <siarhei.siamashka@gmail.com>
*
* SPDX-License-Identifier: GPL-2.0+
*/
/*
* Support for the SSD2828 bridge chip, which can take pixel data coming
* from a parallel LCD interface and translate it on the flight into MIPI DSI
* interface for driving a MIPI compatible TFT display.
*/
#include <common.h>
#include <mipi_display.h>
#include <asm/arch/gpio.h>
#include <asm/gpio.h>
#include "videomodes.h"
#include "ssd2828.h"
#define SSD2828_DIR 0xB0
#define SSD2828_VICR1 0xB1
#define SSD2828_VICR2 0xB2
#define SSD2828_VICR3 0xB3
#define SSD2828_VICR4 0xB4
#define SSD2828_VICR5 0xB5
#define SSD2828_VICR6 0xB6
#define SSD2828_CFGR 0xB7
#define SSD2828_VCR 0xB8
#define SSD2828_PCR 0xB9
#define SSD2828_PLCR 0xBA
#define SSD2828_CCR 0xBB
#define SSD2828_PSCR1 0xBC
#define SSD2828_PSCR2 0xBD
#define SSD2828_PSCR3 0xBE
#define SSD2828_PDR 0xBF
#define SSD2828_OCR 0xC0
#define SSD2828_MRSR 0xC1
#define SSD2828_RDCR 0xC2
#define SSD2828_ARSR 0xC3
#define SSD2828_LCR 0xC4
#define SSD2828_ICR 0xC5
#define SSD2828_ISR 0xC6
#define SSD2828_ESR 0xC7
#define SSD2828_DAR1 0xC9
#define SSD2828_DAR2 0xCA
#define SSD2828_DAR3 0xCB
#define SSD2828_DAR4 0xCC
#define SSD2828_DAR5 0xCD
#define SSD2828_DAR6 0xCE
#define SSD2828_HTTR1 0xCF
#define SSD2828_HTTR2 0xD0
#define SSD2828_LRTR1 0xD1
#define SSD2828_LRTR2 0xD2
#define SSD2828_TSR 0xD3
#define SSD2828_LRR 0xD4
#define SSD2828_PLLR 0xD5
#define SSD2828_TR 0xD6
#define SSD2828_TECR 0xD7
#define SSD2828_ACR1 0xD8
#define SSD2828_ACR2 0xD9
#define SSD2828_ACR3 0xDA
#define SSD2828_ACR4 0xDB
#define SSD2828_IOCR 0xDC
#define SSD2828_VICR7 0xDD
#define SSD2828_LCFR 0xDE
#define SSD2828_DAR7 0xDF
#define SSD2828_PUCR1 0xE0
#define SSD2828_PUCR2 0xE1
#define SSD2828_PUCR3 0xE2
#define SSD2828_CBCR1 0xE9
#define SSD2828_CBCR2 0xEA
#define SSD2828_CBSR 0xEB
#define SSD2828_ECR 0xEC
#define SSD2828_VSDR 0xED
#define SSD2828_TMR 0xEE
#define SSD2828_GPIO1 0xEF
#define SSD2828_GPIO2 0xF0
#define SSD2828_DLYA01 0xF1
#define SSD2828_DLYA23 0xF2
#define SSD2828_DLYB01 0xF3
#define SSD2828_DLYB23 0xF4
#define SSD2828_DLYC01 0xF5
#define SSD2828_DLYC23 0xF6
#define SSD2828_ACR5 0xF7
#define SSD2828_RR 0xFF
#define SSD2828_CFGR_HS (1 << 0)
#define SSD2828_CFGR_CKE (1 << 1)
#define SSD2828_CFGR_SLP (1 << 2)
#define SSD2828_CFGR_VEN (1 << 3)
#define SSD2828_CFGR_HCLK (1 << 4)
#define SSD2828_CFGR_CSS (1 << 5)
#define SSD2828_CFGR_DCS (1 << 6)
#define SSD2828_CFGR_REN (1 << 7)
#define SSD2828_CFGR_ECD (1 << 8)
#define SSD2828_CFGR_EOT (1 << 9)
#define SSD2828_CFGR_LPE (1 << 10)
#define SSD2828_CFGR_TXD (1 << 11)
#define SSD2828_VIDEO_MODE_NON_BURST_WITH_SYNC_PULSES (0 << 2)
#define SSD2828_VIDEO_MODE_NON_BURST_WITH_SYNC_EVENTS (1 << 2)
#define SSD2828_VIDEO_MODE_BURST (2 << 2)
#define SSD2828_VIDEO_PIXEL_FORMAT_16BPP 0
#define SSD2828_VIDEO_PIXEL_FORMAT_18BPP_PACKED 1
#define SSD2828_VIDEO_PIXEL_FORMAT_18BPP_LOOSELY_PACKED 2
#define SSD2828_VIDEO_PIXEL_FORMAT_24BPP 3
#define SSD2828_LP_CLOCK_DIVIDER(n) (((n) - 1) & 0x3F)
/*
* SPI transfer, using the "24-bit 3 wire" mode (that's how it is called in
* the SSD2828 documentation). The 'dout' input parameter specifies 24-bits
* of data to be written to SSD2828. Returns the lowest 16-bits of data,
* that is received back.
*/
static u32 soft_spi_xfer_24bit_3wire(const struct ssd2828_config *drv, u32 dout)
{
int j, bitlen = 24;
u32 tmpdin = 0;
/*
* According to the "24 Bit 3 Wire SPI Interface Timing Characteristics"
* and "TX_CLK Timing Characteristics" tables in the SSD2828 datasheet,
* the lowest possible 'tx_clk' clock frequency is 8MHz, and SPI runs
* at 1/8 of that after reset. So using 1 microsecond delays is safe in
* the main loop. But the delays around chip select pin manipulations
* need to be longer (up to 16 'tx_clk' cycles, or 2 microseconds in
* the worst case).
*/
const int spi_delay_us = 1;
const int spi_cs_delay_us = 2;
gpio_set_value(drv->csx_pin, 0);
udelay(spi_cs_delay_us);
for (j = bitlen - 1; j >= 0; j--) {
gpio_set_value(drv->sck_pin, 0);
gpio_set_value(drv->sdi_pin, (dout & (1 << j)) != 0);
udelay(spi_delay_us);
if (drv->sdo_pin != -1)
tmpdin = (tmpdin << 1) | gpio_get_value(drv->sdo_pin);
gpio_set_value(drv->sck_pin, 1);
udelay(spi_delay_us);
}
udelay(spi_cs_delay_us);
gpio_set_value(drv->csx_pin, 1);
udelay(spi_cs_delay_us);
return tmpdin & 0xFFFF;
}
/*
* Read from a SSD2828 hardware register (regnum >= 0xB0)
*/
static u32 read_hw_register(const struct ssd2828_config *cfg, u8 regnum)
{
soft_spi_xfer_24bit_3wire(cfg, 0x700000 | regnum);
return soft_spi_xfer_24bit_3wire(cfg, 0x730000);
}
/*
* Write to a SSD2828 hardware register (regnum >= 0xB0)
*/
static void write_hw_register(const struct ssd2828_config *cfg, u8 regnum,
u16 val)
{
soft_spi_xfer_24bit_3wire(cfg, 0x700000 | regnum);
soft_spi_xfer_24bit_3wire(cfg, 0x720000 | val);
}
/*
* Send MIPI command to the LCD panel (cmdnum < 0xB0)
*/
static void send_mipi_dcs_command(const struct ssd2828_config *cfg, u8 cmdnum)
{
/* Set packet size to 1 (a single command with no parameters) */
write_hw_register(cfg, SSD2828_PSCR1, 1);
/* Send the command */
write_hw_register(cfg, SSD2828_PDR, cmdnum);
}
/*
* Reset SSD2828
*/
static void ssd2828_reset(const struct ssd2828_config *cfg)
{
/* RESET needs 10 milliseconds according to the datasheet */
gpio_set_value(cfg->reset_pin, 0);
mdelay(10);
gpio_set_value(cfg->reset_pin, 1);
mdelay(10);
}
static int ssd2828_enable_gpio(const struct ssd2828_config *cfg)
{
if (gpio_request(cfg->csx_pin, "ssd2828_csx")) {
printf("SSD2828: request for 'ssd2828_csx' pin failed\n");
return 1;
}
if (gpio_request(cfg->sck_pin, "ssd2828_sck")) {
gpio_free(cfg->csx_pin);
printf("SSD2828: request for 'ssd2828_sck' pin failed\n");
return 1;
}
if (gpio_request(cfg->sdi_pin, "ssd2828_sdi")) {
gpio_free(cfg->csx_pin);
gpio_free(cfg->sck_pin);
printf("SSD2828: request for 'ssd2828_sdi' pin failed\n");
return 1;
}
if (gpio_request(cfg->reset_pin, "ssd2828_reset")) {
gpio_free(cfg->csx_pin);
gpio_free(cfg->sck_pin);
gpio_free(cfg->sdi_pin);
printf("SSD2828: request for 'ssd2828_reset' pin failed\n");
return 1;
}
if (cfg->sdo_pin != -1 && gpio_request(cfg->sdo_pin, "ssd2828_sdo")) {
gpio_free(cfg->csx_pin);
gpio_free(cfg->sck_pin);
gpio_free(cfg->sdi_pin);
gpio_free(cfg->reset_pin);
printf("SSD2828: request for 'ssd2828_sdo' pin failed\n");
return 1;
}
gpio_direction_output(cfg->reset_pin, 0);
gpio_direction_output(cfg->csx_pin, 1);
gpio_direction_output(cfg->sck_pin, 1);
gpio_direction_output(cfg->sdi_pin, 1);
if (cfg->sdo_pin != -1)
gpio_direction_input(cfg->sdo_pin);
return 0;
}
static int ssd2828_free_gpio(const struct ssd2828_config *cfg)
{
gpio_free(cfg->csx_pin);
gpio_free(cfg->sck_pin);
gpio_free(cfg->sdi_pin);
gpio_free(cfg->reset_pin);
if (cfg->sdo_pin != -1)
gpio_free(cfg->sdo_pin);
return 1;
}
/*
* PLL configuration register settings.
*
* See the "PLL Configuration Register Description" in the SSD2828 datasheet.
*/
static u32 construct_pll_config(u32 desired_pll_freq_kbps,
u32 reference_freq_khz)
{
u32 div_factor = 1, mul_factor, fr = 0;
u32 output_freq_kbps;
/* The intermediate clock after division can't be less than 5MHz */
while (reference_freq_khz / (div_factor + 1) >= 5000)
div_factor++;
if (div_factor > 31)
div_factor = 31;
mul_factor = DIV_ROUND_UP(desired_pll_freq_kbps * div_factor,
reference_freq_khz);
output_freq_kbps = reference_freq_khz * mul_factor / div_factor;
if (output_freq_kbps >= 501000)
fr = 3;
else if (output_freq_kbps >= 251000)
fr = 2;
else if (output_freq_kbps >= 126000)
fr = 1;
return (fr << 14) | (div_factor << 8) | mul_factor;
}
static u32 decode_pll_config(u32 pll_config, u32 reference_freq_khz)
{
u32 mul_factor = pll_config & 0xFF;
u32 div_factor = (pll_config >> 8) & 0x1F;
if (mul_factor == 0)
mul_factor = 1;
if (div_factor == 0)
div_factor = 1;
return reference_freq_khz * mul_factor / div_factor;
}
static int ssd2828_configure_video_interface(const struct ssd2828_config *cfg,
const struct ctfb_res_modes *mode)
{
u32 val;
/* RGB Interface Control Register 1 */
write_hw_register(cfg, SSD2828_VICR1, (mode->vsync_len << 8) |
(mode->hsync_len));
/* RGB Interface Control Register 2 */
u32 vbp = mode->vsync_len + mode->upper_margin;
u32 hbp = mode->hsync_len + mode->left_margin;
write_hw_register(cfg, SSD2828_VICR2, (vbp << 8) | hbp);
/* RGB Interface Control Register 3 */
write_hw_register(cfg, SSD2828_VICR3, (mode->lower_margin << 8) |
(mode->right_margin));
/* RGB Interface Control Register 4 */
write_hw_register(cfg, SSD2828_VICR4, mode->xres);
/* RGB Interface Control Register 5 */
write_hw_register(cfg, SSD2828_VICR5, mode->yres);
/* RGB Interface Control Register 6 */
val = SSD2828_VIDEO_MODE_BURST;
switch (cfg->ssd2828_color_depth) {
case 16:
val |= SSD2828_VIDEO_PIXEL_FORMAT_16BPP;
break;
case 18:
val |= cfg->mipi_dsi_loosely_packed_pixel_format ?
SSD2828_VIDEO_PIXEL_FORMAT_18BPP_LOOSELY_PACKED :
SSD2828_VIDEO_PIXEL_FORMAT_18BPP_PACKED;
break;
case 24:
val |= SSD2828_VIDEO_PIXEL_FORMAT_24BPP;
break;
default:
printf("SSD2828: unsupported color depth\n");
return 1;
}
write_hw_register(cfg, SSD2828_VICR6, val);
/* Lane Configuration Register */
write_hw_register(cfg, SSD2828_LCFR,
cfg->mipi_dsi_number_of_data_lanes - 1);
return 0;
}
int ssd2828_init(const struct ssd2828_config *cfg,
const struct ctfb_res_modes *mode)
{
u32 lp_div, pll_freq_kbps, reference_freq_khz, pll_config;
/* The LP clock speed is limited by 10MHz */
const u32 mipi_dsi_low_power_clk_khz = 10000;
/*
* This is just the reset default value of CFGR register (0x301).
* Because we are not always able to read back from SPI, have
* it initialized here.
*/
u32 cfgr_reg = SSD2828_CFGR_EOT | /* EOT Packet Enable */
SSD2828_CFGR_ECD | /* Disable ECC and CRC */
SSD2828_CFGR_HS; /* Data lanes are in HS mode */
/* Initialize the pins */
if (ssd2828_enable_gpio(cfg) != 0)
return 1;
/* Reset the chip */
ssd2828_reset(cfg);
/*
* If there is a pin to read data back from SPI, then we are lucky. Try
* to check if SPI is configured correctly and SSD2828 is actually able
* to talk back.
*/
if (cfg->sdo_pin != -1) {
if (read_hw_register(cfg, SSD2828_DIR) != 0x2828 ||
read_hw_register(cfg, SSD2828_CFGR) != cfgr_reg) {
printf("SSD2828: SPI communication failed.\n");
ssd2828_free_gpio(cfg);
return 1;
}
}
/*
* Pick the reference clock for PLL. If we know the exact 'tx_clk'
* clock speed, then everything is good. If not, then we can fallback
* to 'pclk' (pixel clock from the parallel LCD interface). In the
* case of using this fallback, it is necessary to have parallel LCD
* already initialized and running at this point.
*/
reference_freq_khz = cfg->ssd2828_tx_clk_khz;
if (reference_freq_khz == 0) {
reference_freq_khz = mode->pixclock_khz;
/* Use 'pclk' as the reference clock for PLL */
cfgr_reg |= SSD2828_CFGR_CSS;
}
/*
* Setup the parallel LCD timings in the appropriate registers.
*/
if (ssd2828_configure_video_interface(cfg, mode) != 0) {
ssd2828_free_gpio(cfg);
return 1;
}
/* Configuration Register */
cfgr_reg &= ~SSD2828_CFGR_HS; /* Data lanes are in LP mode */
cfgr_reg |= SSD2828_CFGR_CKE; /* Clock lane is in HS mode */
cfgr_reg |= SSD2828_CFGR_DCS; /* Only use DCS packets */
write_hw_register(cfg, SSD2828_CFGR, cfgr_reg);
/* PLL Configuration Register */
pll_config = construct_pll_config(
cfg->mipi_dsi_bitrate_per_data_lane_mbps * 1000,
reference_freq_khz);
write_hw_register(cfg, SSD2828_PLCR, pll_config);
pll_freq_kbps = decode_pll_config(pll_config, reference_freq_khz);
lp_div = DIV_ROUND_UP(pll_freq_kbps, mipi_dsi_low_power_clk_khz * 8);
/* VC Control Register */
write_hw_register(cfg, SSD2828_VCR, 0);
/* Clock Control Register */
write_hw_register(cfg, SSD2828_CCR, SSD2828_LP_CLOCK_DIVIDER(lp_div));
/* PLL Control Register */
write_hw_register(cfg, SSD2828_PCR, 1); /* Enable PLL */
/* Wait for PLL lock */
udelay(500);
send_mipi_dcs_command(cfg, MIPI_DCS_EXIT_SLEEP_MODE);
mdelay(cfg->mipi_dsi_delay_after_exit_sleep_mode_ms);
send_mipi_dcs_command(cfg, MIPI_DCS_SET_DISPLAY_ON);
mdelay(cfg->mipi_dsi_delay_after_set_display_on_ms);
cfgr_reg |= SSD2828_CFGR_HS; /* Enable HS mode for data lanes */
cfgr_reg |= SSD2828_CFGR_VEN; /* Enable video pipeline */
write_hw_register(cfg, SSD2828_CFGR, cfgr_reg);
return 0;
}
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