From: Jędrzej Boczar Date: Wed, 27 May 2020 06:52:24 +0000 (+0200) Subject: bios/sdram: expose I2C functions X-Git-Tag: 24jan2021_ls180~276^2~1 X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=472bf9ac7196e77c405d99c28696f60f007d5dde;p=litex.git bios/sdram: expose I2C functions --- diff --git a/litex/soc/software/bios/cmds/cmd_litedram.c b/litex/soc/software/bios/cmds/cmd_litedram.c index 1fcce272..17d0bd17 100644 --- a/litex/soc/software/bios/cmds/cmd_litedram.c +++ b/litex/soc/software/bios/cmds/cmd_litedram.c @@ -2,6 +2,7 @@ #include #include +#include #include @@ -222,24 +223,136 @@ define_command(sdrlevel, sdrlevel, "Perform read/write leveling", LITEDRAM_CMDS) define_command(memtest, memtest, "Run a memory test", LITEDRAM_CMDS); #endif +/** + * Command "i2creset" + * + * Reset I2C line state in case a slave locks the line. + * + */ +#ifdef CSR_I2C_BASE +define_command(i2creset, i2c_reset, "Reset I2C line state", LITEDRAM_CMDS); +#endif + +/** + * Command "i2cwr" + * + * Write I2C slave memory using 7-bit slave address and 8-bit memory address. + * + */ +#ifdef CSR_I2C_BASE +static void i2cwr_handler(int nb_params, char **params) +{ + int i; + char *c; + unsigned char write_params[32]; // also indirectly limited by CMD_LINE_BUFFER_SIZE + + if (nb_params < 2) { + printf("i2cwr [, ...]"); + return; + } + + if (nb_params - 1 > sizeof(write_params)) { + printf("Max data length is %d", sizeof(write_params)); + return; + } + + for (i = 0; i < nb_params; ++i) { + write_params[i] = strtoul(params[i], &c, 0); + if (*c != 0) { + printf("Incorrect value of parameter %d", i); + return; + } + } + + if (!i2c_write(write_params[0], write_params[1], &write_params[2], nb_params - 2)) { + printf("Error during I2C write"); + return; + } +} +define_command(i2cwr, i2cwr_handler, "Write over I2C", LITEDRAM_CMDS); +#endif + +/** + * Command "i2crd" + * + * Read I2C slave memory using 7-bit slave address and 8-bit memory address. + * + */ +#ifdef CSR_I2C_BASE +static void i2crd_handler(int nb_params, char **params) +{ + char *c; + int len; + unsigned char slave_addr, addr; + unsigned char buf[256]; + bool send_stop = true; + + if (nb_params < 3) { + printf("i2crd []"); + return; + } + + slave_addr = strtoul(params[0], &c, 0); + if (*c != 0) { + printf("Incorrect slave address"); + return; + } + + addr = strtoul(params[1], &c, 0); + if (*c != 0) { + printf("Incorrect memory address"); + return; + } + + len = strtoul(params[2], &c, 0); + if (*c != 0) { + printf("Incorrect data length"); + return; + } + if (len > sizeof(buf)) { + printf("Max data count is %d", sizeof(buf)); + return; + } + + if (nb_params > 3) { + send_stop = strtoul(params[3], &c, 0) != 0; + if (*c != 0) { + printf("Incorrect send_stop value"); + return; + } + } + + if (!i2c_read(slave_addr, addr, buf, len, send_stop)) { + printf("Error during I2C read"); + return; + } + + dump_bytes((unsigned int *) buf, len, addr); +} +define_command(i2crd, i2crd_handler, "Read over I2C", LITEDRAM_CMDS); +#endif /** * Command "spdread" * * Read contents of SPD EEPROM memory. - * SPD address is defined by the pins A0, A1, A2. + * SPD address is a 3-bit address defined by the pins A0, A1, A2. * */ #ifdef CSR_I2C_BASE +#define SPD_RW_PREAMBLE 0b1010 +#define SPD_RW_ADDR(a210) ((SPD_RW_PREAMBLE << 3) | ((a210) & 0b111)) + static void spdread_handler(int nb_params, char **params) { - unsigned char buf[256]; - unsigned int spdaddr; - int length = sizeof(buf); char *c; + unsigned char spdaddr; + unsigned char buf[256]; + int len = sizeof(buf); + bool send_stop = true; if (nb_params < 1) { - printf("spdread []"); + printf("spdread []"); return; } @@ -254,23 +367,19 @@ static void spdread_handler(int nb_params, char **params) } if (nb_params > 1) { - length = strtoul(params[1], &c, 0); + send_stop = strtoul(params[1], &c, 0) != 0; if (*c != 0) { - printf("Incorrect address"); - return; - } - if (length > sizeof(buf)) { - printf("Max length is %d", sizeof(buf)); + printf("Incorrect send_stop value"); return; } } - if (!spdread(spdaddr, 0, buf, length)) { + if (!i2c_read(SPD_RW_ADDR(spdaddr), 0, buf, len, send_stop)) { printf("Error when reading SPD EEPROM"); return; } - dump_bytes((unsigned int *) buf, length, 0); + dump_bytes((unsigned int *) buf, len, 0); } define_command(spdread, spdread_handler, "Read SPD EEPROM", LITEDRAM_CMDS); #endif diff --git a/litex/soc/software/liblitedram/Makefile b/litex/soc/software/liblitedram/Makefile index 46d71339..c6113c0a 100644 --- a/litex/soc/software/liblitedram/Makefile +++ b/litex/soc/software/liblitedram/Makefile @@ -1,7 +1,7 @@ include ../include/generated/variables.mak include $(SOC_DIRECTORY)/software/common.mak -OBJECTS = sdram.o spd.o +OBJECTS = sdram.o i2c.o all: liblitedram.a diff --git a/litex/soc/software/liblitedram/i2c.c b/litex/soc/software/liblitedram/i2c.c new file mode 100644 index 00000000..af40b8f4 --- /dev/null +++ b/litex/soc/software/liblitedram/i2c.c @@ -0,0 +1,205 @@ +// This file is Copyright (c) 2020 Antmicro + +#include +#include "i2c.h" + +#ifdef CSR_I2C_BASE + +#define I2C_PERIOD_CYCLES (CONFIG_CLOCK_FREQUENCY / I2C_FREQ_HZ) +#define I2C_DELAY(n) cdelay((n)*I2C_PERIOD_CYCLES/4) + +static inline void cdelay(int i) +{ + while(i > 0) { + __asm__ volatile(CONFIG_CPU_NOP); + i--; + } +} + +static inline void i2c_oe_scl_sda(bool oe, bool scl, bool sda) +{ + i2c_w_write( + ((oe & 1) << CSR_I2C_W_OE_OFFSET) | + ((scl & 1) << CSR_I2C_W_SCL_OFFSET) | + ((sda & 1) << CSR_I2C_W_SDA_OFFSET) + ); +} + +// START condition: 1-to-0 transition of SDA when SCL is 1 +static void i2c_start(void) +{ + i2c_oe_scl_sda(1, 1, 1); + I2C_DELAY(1); + i2c_oe_scl_sda(1, 1, 0); + I2C_DELAY(1); + i2c_oe_scl_sda(1, 0, 0); + I2C_DELAY(1); +} + +// STOP condition: 0-to-1 transition of SDA when SCL is 1 +static void i2c_stop(void) +{ + i2c_oe_scl_sda(1, 0, 0); + I2C_DELAY(1); + i2c_oe_scl_sda(1, 1, 0); + I2C_DELAY(1); + i2c_oe_scl_sda(1, 1, 1); + I2C_DELAY(1); + i2c_oe_scl_sda(0, 1, 1); +} + +// Call when in the middle of SCL low, advances one clk period +static void i2c_transmit_bit(int value) +{ + i2c_oe_scl_sda(1, 0, value); + I2C_DELAY(1); + i2c_oe_scl_sda(1, 1, value); + I2C_DELAY(2); + i2c_oe_scl_sda(1, 0, value); + I2C_DELAY(1); + i2c_oe_scl_sda(0, 0, 0); // release line +} + +// Call when in the middle of SCL low, advances one clk period +static int i2c_receive_bit(void) +{ + int value; + i2c_oe_scl_sda(0, 0, 0); + I2C_DELAY(1); + i2c_oe_scl_sda(0, 1, 0); + I2C_DELAY(1); + // read in the middle of SCL high + value = i2c_r_read() & 1; + I2C_DELAY(1); + i2c_oe_scl_sda(0, 0, 0); + I2C_DELAY(1); + return value; +} + +// Send data byte and return 1 if slave sends ACK +static bool i2c_transmit_byte(unsigned char data) +{ + int i; + int ack; + + // SCL should have already been low for 1/4 cycle + i2c_oe_scl_sda(0, 0, 0); + for (i = 0; i < 8; ++i) { + // MSB first + i2c_transmit_bit((data & (1 << 7)) != 0); + data <<= 1; + } + ack = i2c_receive_bit(); + + // 0 from slave means ack + return ack == 0; +} + +// Read data byte and send ACK if ack=1 +static unsigned char i2c_receive_byte(bool ack) +{ + int i; + unsigned char data = 0; + + for (i = 0; i < 8; ++i) { + data <<= 1; + data |= i2c_receive_bit(); + } + i2c_transmit_bit(!ack); + + return data; +} + +// Reset line state +void i2c_reset(void) +{ + int i; + i2c_oe_scl_sda(1, 1, 1); + I2C_DELAY(8); + for (i = 0; i < 9; ++i) { + i2c_oe_scl_sda(1, 0, 1); + I2C_DELAY(2); + i2c_oe_scl_sda(1, 1, 1); + I2C_DELAY(2); + } + i2c_oe_scl_sda(0, 0, 1); + I2C_DELAY(1); + i2c_stop(); + i2c_oe_scl_sda(0, 1, 1); + I2C_DELAY(8); +} + +/* + * Read slave memory over I2C starting at given address + * + * First writes the memory starting address, then reads the data: + * START WR(slaveaddr) WR(addr) STOP START WR(slaveaddr) RD(data) RD(data) ... STOP + * Some chips require that after transmiting the address, there will be no STOP in between: + * START WR(slaveaddr) WR(addr) START WR(slaveaddr) RD(data) RD(data) ... STOP + */ +bool i2c_read(unsigned char slave_addr, unsigned char addr, unsigned char *data, unsigned int len, bool send_stop) +{ + int i; + + i2c_start(); + + if(!i2c_transmit_byte(I2C_ADDR_WR(slave_addr))) { + i2c_stop(); + return false; + } + if(!i2c_transmit_byte(addr)) { + i2c_stop(); + return false; + } + + if (send_stop) { + i2c_stop(); + } + i2c_start(); + + if(!i2c_transmit_byte(I2C_ADDR_RD(slave_addr))) { + i2c_stop(); + return false; + } + for (i = 0; i < len; ++i) { + data[i] = i2c_receive_byte(i != len - 1); + } + + i2c_stop(); + + return true; +} + +/* + * Write slave memory over I2C starting at given address + * + * First writes the memory starting address, then writes the data: + * START WR(slaveaddr) WR(addr) WR(data) WR(data) ... STOP + */ +bool i2c_write(unsigned char slave_addr, unsigned char addr, const unsigned char *data, unsigned int len) +{ + int i; + + i2c_start(); + + if(!i2c_transmit_byte(I2C_ADDR_WR(slave_addr))) { + i2c_stop(); + return false; + } + if(!i2c_transmit_byte(addr)) { + i2c_stop(); + return false; + } + for (i = 0; i < len; ++i) { + if(!i2c_transmit_byte(data[i])) { + i2c_stop(); + return false; + } + } + + i2c_stop(); + + return true; +} + +#endif /* CSR_I2C_BASE */ diff --git a/litex/soc/software/liblitedram/i2c.h b/litex/soc/software/liblitedram/i2c.h new file mode 100644 index 00000000..c0cc2bfe --- /dev/null +++ b/litex/soc/software/liblitedram/i2c.h @@ -0,0 +1,19 @@ +#ifndef __I2C_H +#define __I2C_H + +#include +#include + +/* I2C frequency defaults to a safe value in range 10-100 kHz to be compatible with SMBus */ +#ifndef I2C_FREQ_HZ +#define I2C_FREQ_HZ 50000 +#endif + +#define I2C_ADDR_WR(addr) ((addr) << 1) +#define I2C_ADDR_RD(addr) (((addr) << 1) | 1u) + +void i2c_reset(void); +bool i2c_write(unsigned char slave_addr, unsigned char addr, const unsigned char *data, unsigned int len); +bool i2c_read(unsigned char slave_addr, unsigned char addr, unsigned char *data, unsigned int len, bool send_stop); + +#endif /* __I2C_H */ diff --git a/litex/soc/software/liblitedram/sdram.h b/litex/soc/software/liblitedram/sdram.h index 0c8cae9e..7deb82e3 100644 --- a/litex/soc/software/liblitedram/sdram.h +++ b/litex/soc/software/liblitedram/sdram.h @@ -2,7 +2,7 @@ #define __SDRAM_H #include -#include "spd.h" +#include "i2c.h" void sdrsw(void); void sdrhw(void); diff --git a/litex/soc/software/liblitedram/spd.c b/litex/soc/software/liblitedram/spd.c deleted file mode 100644 index 3f396e78..00000000 --- a/litex/soc/software/liblitedram/spd.c +++ /dev/null @@ -1,180 +0,0 @@ -// This file is Copyright (c) 2020 Antmicro - -#include -#include "spd.h" - -#ifdef CSR_I2C_BASE - -// SMBus uses frequency 10-100 kHz -#define I2C_FREQ_HZ 50000 -#define I2C_PERIOD_CYCLES (CONFIG_CLOCK_FREQUENCY / I2C_FREQ_HZ) -#define I2C_DELAY(n) cdelay((n)*I2C_PERIOD_CYCLES/4) - -static void cdelay(int i) -{ - while(i > 0) { - __asm__ volatile(CONFIG_CPU_NOP); - i--; - } -} - -static void i2c_oe_scl_sda(int oe, int scl, int sda) -{ - i2c_w_write( - ((oe & 1) << CSR_I2C_W_OE_OFFSET) | - ((scl & 1) << CSR_I2C_W_SCL_OFFSET) | - ((sda & 1) << CSR_I2C_W_SDA_OFFSET) - ); -} - - -// START condition: 1-to-0 transition of SDA when SCL is 1 -static void i2c_start(void) -{ - i2c_oe_scl_sda(1, 1, 1); - I2C_DELAY(1); - i2c_oe_scl_sda(1, 1, 0); - I2C_DELAY(1); - i2c_oe_scl_sda(1, 0, 0); - I2C_DELAY(1); -} - -// STOP condition: 0-to-1 transition of SDA when SCL is 1 -static void i2c_stop(void) -{ - i2c_oe_scl_sda(1, 0, 0); - I2C_DELAY(1); - i2c_oe_scl_sda(1, 1, 0); - I2C_DELAY(1); - i2c_oe_scl_sda(1, 1, 1); - I2C_DELAY(1); - i2c_oe_scl_sda(0, 1, 1); -} - -// Reset line state -static void i2c_reset(void) -{ - int i; - i2c_oe_scl_sda(1, 1, 1); - I2C_DELAY(8); - for (i = 0; i < 9; ++i) { - i2c_oe_scl_sda(1, 0, 1); - I2C_DELAY(2); - i2c_oe_scl_sda(1, 1, 1); - I2C_DELAY(2); - } - i2c_oe_scl_sda(0, 0, 1); - I2C_DELAY(1); - i2c_stop(); - i2c_oe_scl_sda(0, 1, 1); - I2C_DELAY(8); -} - -// Call when in the middle of SCL low, advances one clk period -static void i2c_transmit_bit(int value) -{ - i2c_oe_scl_sda(1, 0, value); - I2C_DELAY(1); - i2c_oe_scl_sda(1, 1, value); - I2C_DELAY(2); - i2c_oe_scl_sda(1, 0, value); - I2C_DELAY(1); - i2c_oe_scl_sda(0, 0, 0); // release line -} - -// Call when in the middle of SCL low, advances one clk period -static int i2c_receive_bit(void) -{ - int value; - i2c_oe_scl_sda(0, 0, 0); - I2C_DELAY(1); - i2c_oe_scl_sda(0, 1, 0); - I2C_DELAY(1); - // read in the middle of SCL high - value = i2c_r_read() & 1; - I2C_DELAY(1); - i2c_oe_scl_sda(0, 0, 0); - I2C_DELAY(1); - return value; -} - -// Send data byte and return 1 if slave sends ACK -static int i2c_transmit(unsigned char data) -{ - int ack; - int i; - - // SCL should have already been low for 1/4 cycle - i2c_oe_scl_sda(0, 0, 0); - for (i = 0; i < 8; ++i) { - // MSB first - i2c_transmit_bit((data & (1 << 7)) != 0); - data <<= 1; - } - ack = i2c_receive_bit(); - - // 0 from slave means ack - return ack == 0; -} - -// Read data byte and send ACK if ack=1 -static unsigned char i2c_receive(int ack) -{ - unsigned char data = 0; - int i; - - i2c_oe_scl_sda(0, 0, 0); - I2C_DELAY(1); - for (i = 0; i < 8; ++i) { - data <<= 1; - data |= i2c_receive_bit(); - } - i2c_transmit_bit(!ack); - - return data; -} - - -#define ADDR_PREAMBLE_RW 0b1010 -#define ADDR_7BIT(addr) ((ADDR_PREAMBLE_RW << 3) | ((addr) & 0b111)) -#define ADDR_WRITE(addr) ((ADDR_7BIT(addr) << 1) & (~1u)) -#define ADDR_READ(addr) ((ADDR_7BIT(addr) << 1) | 1u) - -/* - * Read SPD memory content - * - * spdaddr: address of SPD EEPROM defined by pins A0, A1, A2 - * addr: memory starting address - */ -int spdread(unsigned int spdaddr, unsigned int addr, unsigned char *buf, unsigned int len) { - int i; - - i2c_reset(); - - // To read from random address, we have to first send a "data-less" WRITE, - // followed by START condition with a READ (no STOP condition) - i2c_start(); - - if(!i2c_transmit(ADDR_WRITE(spdaddr))) { - i2c_reset(); - return 0; - } - if(!i2c_transmit(addr)) { - i2c_reset(); - return 0; - } - - I2C_DELAY(1); - i2c_start(); - if(!i2c_transmit(ADDR_READ(spdaddr))) { - i2c_reset(); - return 0; - } - for (i = 0; i < len; ++i) { - buf[i] = i2c_receive(i != len - 1); - } - i2c_stop(); - - return 1; -} -#endif /* CSR_I2C_BASE */ diff --git a/litex/soc/software/liblitedram/spd.h b/litex/soc/software/liblitedram/spd.h deleted file mode 100644 index 54b04e34..00000000 --- a/litex/soc/software/liblitedram/spd.h +++ /dev/null @@ -1,8 +0,0 @@ -#ifndef __SPD_H -#define __SPD_H - -#include - -int spdread(unsigned int spdaddr, unsigned int addr, unsigned char *buf, unsigned int len); - -#endif /* __SPD_H */