i2c_tca9548.h

// Copyright 2023-2025 The Aerospace Corporation.
// This file is a part of SatCat5, licensed under CERN-OHL-W v2 or later.
// Device driver for PCA9548A / TCA9548A I2C switches.
 
#pragma once
 
#include <satcat5/cfg_i2c.h>
#include <satcat5/utils.h>
 
#ifndef SATCAT5_I2C_MAXCMD
#define SATCAT5_I2C_MAXCMD  16      // Each queue up to N transactions
#endif
 
namespace satcat5 {
    namespace device {
        namespace i2c {
            class Tca9548
                : public satcat5::cfg::I2cGeneric
                , public satcat5::cfg::I2cEventListener
            {
            public:
                Tca9548(
                    satcat5::cfg::I2cGeneric* i2c,          // Parent interface
                    const satcat5::util::I2cAddr& devaddr); // Device address
 
                bool select_mask(u8 mask);
 
                inline bool select_channel(unsigned n)
                    {return select_mask((u8)(1u << n));}
 
                // Forward read/write calls to the parent.
                bool busy() override;
                bool read(const satcat5::util::I2cAddr& devaddr,
                    u8 regbytes, u32 regaddr, u8 nread,
                    satcat5::cfg::I2cEventListener* callback = 0) override;
                bool write(const satcat5::util::I2cAddr& devaddr,
                    u8 regbytes, u32 regaddr, u8 nwrite, const u8* data,
                    satcat5::cfg::I2cEventListener* callback = 0) override;
 
            protected:
                // Forward callbacks to the original caller.
                void i2c_done(
                    bool noack, const satcat5::util::I2cAddr& devaddr,
                    u32 regaddr, unsigned nread, const u8* rdata) override;
 
                // Calculate write-index for the circular buffer.
                inline unsigned cb_wridx() const
                    {return satcat5::util::modulo_add_uns(m_cb_rdidx + m_cb_count, SATCAT5_I2C_MAXCMD);}
 
                // Pointer to the parent interface.
                satcat5::cfg::I2cGeneric* const m_parent;
                const satcat5::util::I2cAddr m_devaddr;
 
                // Circular queue of pending callbacks.
                unsigned m_cb_count;
                unsigned m_cb_rdidx;
                satcat5::cfg::I2cEventListener* m_cb_queue[SATCAT5_I2C_MAXCMD];
            };
 
            typedef satcat5::device::i2c::Tca9548 Pca9548;
        }
    }
}